Resumo em Inglês:

This work aims to deposit silica (SiO2) on polyamide 6,6 fabrics by hybrid corona-dielectric barrier discharge plasma at atmospheric pressure. The reactor used, developed at the Laboratory of Plasma and Processes of the Aeronautics Institute of Technology (LPP/ITA), allows the treatment of fabric surfaces by activation and plasma deposition processes, aiming, in this order, the alteration of wettability and the deposition of silica on its surface, using a silicic acid solution (Si(OH)4) as a silica precursor. The morphology of the deposited films was evaluated by scanning electron microscopy (SEM). To identify the chemical modifications generated by the plasma treatment, the untreated and treated samples were analyzed by Fourier transform infrared spectroscopy with attenuated reflectance (FTIR-ATR) and Energy Dispersive Spectroscopy (EDS). The thermal behavior of the treated and untreated samples was evaluated by Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, X-ray diffraction (XRD) was also used to identify crystalline phases in the film. The results showed that plasma processing proved to be an effective technique for modifying the surface characteristics of polyamide 6,6.

Resumo em Inglês:

This study presents a detailed analysis of the feasibility of Ti-15Mo alloy for coronary stents by independently applying the TOPSIS and RADAR multi-parameter selection methods independently and comparing the results obtained. The research focused on evaluating β-metastable titanium alloys for use in coronary stents, employing the TOPSIS and RADAR methods for a comprehensive and independent analysis. The independent application of these methods enabled for a robust and detailed comparison between different candidate materials, considering crucial criteria such as mechanical strength, biocompatibility, and cost-effectiveness. The results showed that the Ti-15Mo alloy excelled in terms of safety and mechanical performance in both methodologies, offering a combination of mechanical properties and biological compatibility suitable for this application. Compared to 316L stainless steel and Co-Cr L605, Ti-15Mo consistently outperformed across multiple criteria. This study positions Ti-15Mo as a promising candidate for coronary stents and emphasizes the effectiveness of combining TOPSIS and RADAR methodologies for comprehensive material selection in biomedical applications. The research underscores the importance of detailed and methodological evaluation to optimize the performance and safety of advanced biomedical devices.

Resumo em Inglês:

This study characterized wastes from scheelite and columbite-tantalite mining, as well as kaolin processing, to produce microfiltration membranes for wastewater treatment using a fast-sintered process. After characterization, the wastes were mixed with clays, pressed, and sintered at low temperatures of 1050 and 1100 °C. The resulting membranes exhibited pore size distributions ranging from 3 μm to 180 μm and flexural strengths exceeding 14 MPa. In a crossflow filtration system, permeate fluxes ranged from 177 L/h.m2 to 228 L/h.m2 at 2 bar, with permeabilities from 99 to 130 L/h.m2 bar depending on the waste content. Membranes with smaller pore sizes effectively removed 90% to 96% of turbidity from a water/clay suspension containing micrometric clay particles. This approach demonstrates that rapid sintering of ceramic membranes from mining waste can effectively reduce environmental impacts and energy costs, providing a sustainable solution for wastewater treatment.

Resumo em Inglês:

We followed the microstructural evolution of UNS S32205 duplex stainless steel during cold rolling up to 79% reduction in thickness and at early stages of isothermal annealing at 1080ºC. Qualitative analysis of peak broadening and kernel average misorientation (KAM) parameter obtained by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD), respectively, indicated a higher work hardening of austenite. Strain-induced martensite was not detected within this strain range by using X-ray diffraction and DC-magnetisation measurements. Two particular rolling thickness reductions were chosen for recrystallisation studies; i.e., 43% and 64%. After annealing for 1 min, primary recrystallisation occurred in ferrite (42% of recrystallised grains for 43% cold rolling), whereas austenite only recovered. For a reduction of 64%, the recrystallised fraction of ferrite did not change significantly, while austenite reached a recrystallised fraction of 43%. Full recrystallisation is noticed after annealing for 3 min for both conditions resulting in a bamboo-like grain structure.

Resumo em Inglês:

Corrosion of reinforcing bars in reinforced concrete significantly compromises the durability of structures. In aggressive environments, measures such as galvanization are common, but surface treatments with zinc chromate (Cr6+), a carcinogenic compound, demand safer alternatives. Organic acids, especially oxalic acid, have shown promise in acidic environments, but their efficacy under alkaline conditions is uncertain. This study evaluates the zinc oxalate conversion coating on galvanized steel exposed to corrosive environments with varied pH. Galvanized sheets were treated with oxalic acid [0.1 m] and exposed to alkaline solutions (pH 13) and slightly acidic nacl solutions (ph 6.5). Corrosion resistance tests and analyses of phase formation (XRD) and morphology (SEM) were conducted. Results showed that the zinc oxalate film acts as a physical barrier in acidic conditions but dissolves in alkaline environments, demonstrating ineffectiveness. In NaCl solution, treatment with oxalic acid promotes the formation of a zinc oxalate layer, which accelerates the formation of corrosion products and improves resistance to corrosive attack. In contrast, treatment with an alkaline solution results in a less effective passivation layer, offering limited protective effects and leading to a higher corrosion rate over time.

Resumo em Inglês:

Zirconia-toughened alumina (ZTA) is a promising material for dentistry; however, its current formulation exhibits a mauve coloration. This study aimed to synthesize a white ZTA ceramic by doping it with 0.7 wt% magnesium oxide (MgO). Specimens (1.2 mm in thickness x 12 mm in diameter) were divided into 3 groups (n = 15): ZTA doped with chromium oxide (ZTA-Cr2O3), ZTA doped with MgO (ZTA-MgO) and ICE-Zirkon (control group). The materials were analyzed using X-ray diffraction, energy-dispersive X-ray fluorescence spectrometer, scanning electron microscopy, and spectrophotometer. Biaxial flexural strength was conducted, and the Weibull modulus (m) and probability of failure were calculated. ZTA-MgO group had a white color, showing the pattern for alumina and zirconia grains in ZTA with a typical composition of the materials. It demonstrated superior BFS (915 ±41 MPa) and higher reliability than the ZTA-Cr2O3. ZTA-MgO proved to be able to produce white ZTA for future use in dentistry.

Resumo em Inglês:

Hybrid metal matrix composites (MMCs) have a higher potential for widespread use in structural engineering and functional device applications because they show better overall mechanical and functional response than their conventional equivalents. Silicon Carbide (SiC) and Yttrium Oxide (Y2O3) reinforced Copper hybrid composites were produced by powder metallurgy (PM) process sequence. Both the reinforcements were included in the wt. % of 2.5, 5.0 and 7.5. The homogeneous presence of SiC and Y2O3 particles in copper MMC’s was confirmed by morphology and characterization studies. The blended milled powders were produced in the form of cylindrical billets using a punch and die arrangement, by cold compaction method at 400 MPa pressure, in a hydraulic press. Sintering was carried out at 900°C for 5 hours in a Box furnace. The inclusion of SiC and Y2O3 in the copper matrix composites improved the density, hardness, compressive strength (CS), wear resistance and decreased the corrosion rate (CR).Pin on disc (POD) experiments was conducted to study the wear behavior of the composite samples. The minimum wear rate (WR) 3.31049 x 10-4 mm3/m was obtained for the composite contain 7.5 wt. % of SiC and 7.5 wt. % of Y2O3.

Resumo em Inglês:

The present study investigates friction stir welded AA6065-10% Al2O3MMC by incorporating varying percentages of heat treated biosilica. The biosilica is first extracted from waste cassava peel, and it is heated under 1500°C, to get properly arranged crystalline structured biosilica particle. During friction stir welding process, the biosilica particle is dispersed around the welded zone, which in turn impacts load carrying capacity of the material. The study revealed that 3 vol.% of biosilica infused FSW composite ‘C’ shows maximum tensile strength of 276 MPa, yield strength of 238 MPa, impact energy of 20.8 J, elongation of 5.2%, fatigue strength of 176 MPa. Further, the 5 vol.% of biosilica infused FSW composite ‘D’ shows hardness strength of 121 Hv. Additionally, it has been discovered under microstructural analysis that the inclusion of fine-grained heat-treated biosilica exhibits the greatest dispersion of biosilica within the nugget zone, heat affected zone, and thermo mechanically affected zone, which affects the composite's overall strength characteristics. Thus, because of their less dense, better thermo mechanical properties, it could be influenced in areas where joint application, load bearing are needed such as aerospace, heavy industrial, infrastructural, transport and military sector.

Resumo em Inglês:

Materials based on doped ceria are considered promising elements for applications in solid oxide fuel cells (SOFCs). Cerium oxide can be classified as a mixed conductor. The type of dopant also greatly influences properties of doped ceria. Hence, studying the type of dopant to be used in the synthesis process is of great importance. Recent studies have shown that the lanthanide or alkaline earth ions are the most commonly dopants used in ceria. In order to obtain nanometric powders, which favor the catalytic effect and are more reactive than other powders, a technique of obtaining powders via solution combustion synthesis (SCS) was selected, and the type of fuel used, and its excess (content) were analyzed. The parameters that were varied in this study were related to the dopant (Ce(1-x) La(x) O(2- δ), where x = 0.1, 0.2, 0.3) and the type of fuel used (urea or sucrose) The powders were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the TGA, a significant increase in the remaining mass loss was observed with an increase in the dopant content when both urea and sucrose were used. The SCS method enabled the production of lanthanum oxide doped ceria phase using both fuels. The XRD of the samples obtained using urea as fuel exhibited well-defined, narrow, and intense peaks immediately after synthesis, and this characteristic was maintained after thermal treatment. On the other hand, the use of sucrose as fuel enables the production of the same cristalinity after thermal treatment at 850°C. In addition, these samples had a higher specific surface area and smaller crystallite size compared to those obtained using urea as fuel.

Resumo em Inglês:

Aluminum Metal matrix composites (AMMCs) have gained significant attention in the automotive and aerospace industries due to their outstanding mechanical properties, combined with their lightweight and fuel-efficient characteristics. AMMCs have also garnered significant attention from researchers due to their potential to minimize the wear of counter face materials. This study investigates the dry sliding wear behavior of aluminum-based hybrid MMCs using an experimental approach. Friction Stir Welding (FSW) has emerged as a promising solid-state technique for welding AMMCs. The FSW experiments were designed using a Central Composite Rotatable Design (CCRD) with four factors and five levels. Empirical models were developed to predict the influence of FSW process parameters including tool rotational speed (TRS), Welding Speed (WS), Axial Load (AL), and the percentage of Boron Carbide (B4C) reinforcement on key properties such as wear rate and wear resistance of the AMMCs. The developed regression model was developed to minimize the wear rate using response surface methodology (RSM) method and predicted wear rate is found to be 154.21 x 10-5 mm3/m. The maximum percentage errors for predicting optimal Wear Rate, and Wear Resistance (WR) were + 5.39%, and + 2.65%, respectively. The wear resistance of the AMMCs was also improved by following Friction Stir Welding (FSW).

Resumo em Inglês:

This study aims the applicability and efficacy of a new DC water plasma method at low temperature, for the sterilization of titanium contaminated samples and its effects on the surface oxide layer and morphological structure. The plasma treatment was carried out at a temperature of 60°C, for a predefined time of 10 minutes. Water vapor was generated from distilled water and polarized at -700 V during plasma-on period. Elemental analysis revealed that Ti surfaces showed a complete absence of organic and inorganic molecules (0% at detected /0.1% sensitivity) and complete bacteria elimination. Additionally, the oxygen content remained around 8% indicating a positive outcome for bioactivity titanium surface due to oxide presence. Initial results support that the water plasma system enables effective elimination of surface microorganisms while enhancing the natural oxide layer make up of titanium using a low temperature and water-based sterilization system that can be envisioned for clinical use.

Resumo em Inglês:

Calcium addition to steels normally aims at modifying inclusions to improve castability and cleanliness. This study investigated the inclusion modification efficiency in liquid steel for three conditions varying injection timing: all Ca after RH degasser, all Ca before RH degasser and split addition. Six industrial heats were produced at Usiminas Steelworks, two for each condition. The heats were sampled for automated SEM/EDS inclusion analysis and total oxygen and the results compared to computational thermodynamics simulations. Inclusion modification was most efficient for the split addition condition. This condition was the closest to the calculated castability window, resulting in low inclusion density, a higher percentage of liquid inclusions during casting and lower CaS formation. Furthermore, computational thermodynamic simulations and inclusion analysis presented good agreement. These findings not only enhance the understanding of calcium treatment in steel production but also provide practical insights for optimizing the calcium addition process.

Resumo em Inglês:

In this paper, four negative re-entrant hexagonal honeycomb (NRHH) porous scaffolds with different extension angles θ (15°, 30°, 45° and 60°) cell structures were designed and their preparation was accomplished by selective laser melting (SLM) in 3D printing technology so that Negative Poisson Ratio metamaterials could be applied to bone implants to treat bone defects. The effects of structural design on residual stress, surface roughness, and compressive properties of NRHH porous scaffolds were evaluated by finite element analysis and experimental analysis. The results showed that the 15°-NRHH porous scaffold exhibited optimal performance. When the θ angle increased, the scaffold introduced increased residual stresses, increased surface roughness, generated increased deformation, stress, and strain, and decreased compressive performance.

Resumo em Inglês:

Volatile corrosion inhibitors (VCIs) are used to protect metal objects temporarily, such as during storage and transport. Although widely used, in the last two decades traditional synthetic VCIs have been gradually replaced due to their high toxicity. A viable solution is the use of natural inhibitors. The objective of this study was to evaluate the efficiency of limonene-based natural VCI to protect AISI 1020 carbon steel against corrosion. The vaporization capacity of VCI was evaluated by the standardized sublimation test; the ability to form a protective barrier was analyzed by testing kraft paper as anticorrosive packaging; and the inhibition mechanisms against carbon steel corrosion were investigated by electrochemical methods of open circuit potential (OCP) measurement, potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). According to the sublimation test, limonene-based VCI provided effective protection to the carbon steel at a concentration of 1.5 g/L. The kraft paper test confirmed the efficiency of the temporary use (4 days) of the natural VCI in packaging, without residue deposition. Furthermore, through electrochemical measurements, we found that limonene-based VCI provided an inhibition efficiency of 99% to AISI 1020 carbon steel in a 3.5% NaCl aqueous solution, thus identifying a potential alternative to toxic synthetic VCIs.

Resumo em Inglês:

This study investigated the kinetics and thermodynamics of starch acetylation and examined the influence of the degree of substitution (DS) on the properties of acetylated starches. Starch acetylation kinetics followed a pseudo-first-order model, reaching a degree of substitution of 2.62 after 50 minutes. Negative enthalpy and entropy values revealed a non-spontaneous reaction requiring catalysis. Fourier Transform Infrared Spectroscopy confirmed acetylation through the appearance of a carbonyl band and the reduction of the glycosidic bond peak. Increasing degree of substitution caused granule breakage, agglutination, and reduced crystallinity, as evidenced by Scanning Electron Microscopy and X-Ray Diffraction. Dynamic Mechanical Analysis demonstrated that these structural changes reduced the glass transition in high degrees of substitution (DS 2.62) and enhanced thermal stability and viscoelastic properties due to the loss of crystallinity. Understanding these processes facilitates the industrial optimization of starch acetylation, resulting in modified starches with improved properties for diverse applications.

Resumo em Inglês:

This study investigates the impact of porosity on the mechanical properties of aluminum matrix composites reinforced with ceramic particles, focusing on the optimization of volume fraction and porosity to enhance tensile strength. Using Finite Element Analysis (FEA) and Analysis of Variance (ANOVA), the effects of varying volume fractions (5%, 10%, 15%, 20%, and 25%) and porosity levels (1%, 2%, 3%, 4%, and 5%) on Von Mises stresses were systematically analyzed. The results demonstrated that as porosity increased, Von Mises stress also increased, while higher volume fractions contributed to better stress distribution and enhanced mechanical properties. Optimization analysis identified the optimal parameters as a volume fraction of 25%, porosity level of 1.01%, particle size of 30.083 µm, and pore diameter of 9.020 µm, achieving a desirability score of 0.895 and a Von Mises stress of 9.06E-08 N/µm2. The ANOVA results confirmed the statistical significance of these parameters, with a P-value threshold of <0.05. These insights are crucial for understanding how to optimize porosity and reinforcement in composite materials, providing valuable guidance for applications in the aerospace and automotive industries, where lightweight and high-strength materials are vital.

Resumo em Inglês:

Given the vast universe of high-entropy alloys (HEAs), solid solution formation (SSF) prediction is increasingly relevant. The processing route leads to uncertainty in the mass of each alloy component, affecting SSF. Furthermore, investigations led to atomic radius modification under interaction with neighboring atoms, also influencing SSF. Therefore, this paper presents an uncertainty quantification framework implemented over the thermophysical parameters calculation (TPC) approach to verify the behavior of the SSF parameters as the mass of the alloy components vary and the atomic radii are modified. The AlCrFeMoNbTaTiVW alloy was subjected to this framework, being the tungsten mass the most influential, and tantalum the less influential overall. Moreover, the atomic radii modification does not work properly under TPC theory, implying in non-SSF prediction even when a solid solution is formed. Thenceforth, equimolar HEAs are now near-equimolar, and the SSF parameters may indicate that some samples of the same alloy batch may result in SSF, others not.

Resumo em Inglês:

Heat dissipation materials with high thermal conductivity (TC) can meet the high demand for improving heat dissipation in high-power IGBT modules. The current study focused on soldering Al-graphite composites (Al-Gr) with a copper (Cu) base plate using an active type Sn-Ag-Ti (SAT) solder. Ultrasonic active soldering (UAS) was performed in air at 250 °C for 30 sec. The relative spreadability rates of the direct UAS process versus conventional soldering were + 276.6% for SAT/Cu and +186.1% for SAT/Al-Gr. After direct UAS, a Cu6Sn5 layer formed at the active solder/Cu interface and Al dissolved into the active solder zone, thus forming a ternary coarse Al-Ag-Sn solid solution in the active solder region. In addition, submicron particles (e.g., Al-Ag-Sn and Ag3Sn) adsorbed on the surface of active solder/Gr interface. The calculated Gibbs free energy results indicated that both solute Ti and Ti-Sn compounds could react with C to form TiC compounds, and TiC reacted with Ti-Sn compounds to form the Ti2SnC phase, which was accelerated with the direct UAS process. The shear strengths were measured to be 31.0 ± 4.1MPa for Cu/SAT/Cu joints, 14.3 ± 3.2 MPa for Al-Gr/SAT/Cu joints, and 12.8 ± 3.8 MPa for Al-Gr/SAT/Al-Gr joints, respectively.

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The mineralization process to reach Tungsten (W) involves several steps to reduce the impurities (residues), which makes the process more expensive. However, it is possible to explore the pure scheelite (CaWO4) and residue doped-CaWO4 on flexible sheets using the Tape Casting technique. In particular, the high frequency dielectric properties of flexible multilayers have an increased appeal in the electronics industry. In this study, we present a systematic investigation of structural, morphological, electrical and high-frequency dielectric properties of flexible ceramics sheet multilayers composed of pure CaWO4 and residue-doped CaWO4. Our findings demonstrate that the dielectric constant has a small dependence on the residue amount, but a remarkable modification in the dielectric constant as the number of layers increases. Here we achieved a 34% increase in the dielectric constant for pure CaWO4 flexible ceramic sheets when the number of layers increased from 1 to 3.

Resumo em Inglês:

Although biocomposite foams have been used as wound dressings, achieving accelerated healing with reduced complications requires precise control of exudate absorption and evaporation. This study evaluated the fluid handling capacity, water vapor transmission, and cytotoxicity of novel chitosan/bioactive glass composite foams. Prepared following a simple process, these foams have up to 60% porosity and interconnected pore networks. Cytotoxicity assays confirmed their non-toxicity to L-929 fibroblast cells. The foams demonstrated a liquid absorption capacity of up to 160%, with improved performance at higher levels of bioactive glass. Fluid handling tests showed effective moisture absorption and transfer, making these dressings suitable for the treatment of wounds such as burns and pressure ulcers. The water vapor transmission test confirmed the ability of the foams to promote high exudate removal rates, suggesting that chitosan/bioactive glass composites are promising for wound dressing applications.

Resumo em Inglês:

Traditional biomaterials like CoCrMo, Ti, and stainless-steel face challenges due to their instability in biological settings. As an alternative, exploring multicomponent alloys is viewed as a viable path for bettering both mechanical performance and biocompatibility. Our research explores the potentiality of the MoNbNiTiZr based alloy for biomedical applications. The microstructural characterization was realized using X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM/EDS). We also conducted Vickers microhardness tests and assessed it’s in vitro biocompatibility and antibacterial action against S. aureus and S. aureus HU25 strains relative to cp-Ti. Our observations denote that this alloy showcases a triphasic structure, consisting of dendritic and interdendritic zones with BCC, HCP, and Laves formations. A microhardness of is approximately 576.5 HV align with values for comparable multicomponent alloys in the biomedical field. Pertaining to its antibacterial efficiency and in vitro compatibility, this alloy manifests commendable antibacterial performance and relevant compatibility in comparison with cp-Ti.

Resumo em Inglês:

This study investigates the effects of different post-weld heat treatments (PWHT) on the mechanical properties and microstructure of ASTM 335 Gr P91 martensitic steel, commonly used in boiler applications. Mechanical tests were conducted at room temperature, 300°C, and 600°C. Two PWHT conditions were applied: (i) PWHT-1, involving a 300°C isothermal treatment followed by heating to 770°C, and (ii) PWHT-2, following the same profile but without cooling to room temperature after the initial isothermal step. The resulting microstructure exhibited martensitic features, with a gradient of prior austenite grain boundaries in the heat-affected zone (HAZ) and δ-ferrite formation in the fusion zone (FZ), reducing toughness. Ultimate tensile strength decreased with increasing temperature, ranging from 675–750 MPa (RT), 525–615 MPa (300°C), and 375–440 MPa (600°C). Elongation was highest at 600°C (BM: 25–30%, FZ: 8–20%), decreasing at room temperature (BM: 20–25%, FZ: 2–12%). Toughness tests showed crack propagation across BM, HAZ, and FZ, with the lowest energy absorption in FZ (0.05–0.4 mm, 12–50 J). At 600°C, toughness decreased in BM and HAZ but increased in FZ, suggesting a change in deformation mechanisms at elevated temperatures.

Resumo em Inglês:

Compared with other metal implant materials, titanium has become the preferred material for hard tissue substitutes and restorations. However, titanium implants are bioinert and cannot effectively promote adhesion or proliferation of bone marrow mesenchymal stem cells (BMSCs) after implantation in vivo. In this study, a microporous Cu-doped titanium dioxide (Cu-TiO2) film was prepared on a titanium surface via microarc oxidation. This film not only has a good porous surface morphology, with Cu distributed on the surface of the film, but also improves the surface roughness and hydrophilicity of titanium. In vitro cell experiments revealed that the Cu-TiO2 film has good biocompatibility and bioactivity and enables adhesion and growth of BMSCs. In addition, the Cu-TiO2 film can promote the expression of integrin β1 in BMSCs. This study enhances our understanding of the interactions between titanium implants and cells and provides a theoretical basis for the clinical application of Cu-TiO2 films.

Resumo em Inglês:

This study investigates the torsional fatigue behavior of Ti-15Mo alloy through comprehensive analyses of its mechanical properties, microstructure, fatigue stress-life curves, and fracture surfaces, providing valuable insights into its fatigue characteristics. The hot-forged and air-cooled Ti15Mo alloy exhibited a microstructure predominantly consisting of equiaxial β phase grains, deformation twins, and ω athermal phase. Mechanical testing revealed a microhardness of 347.4 HV, yield and ultimate tensile strengths of 873 MPa, elongation of 20.7%, Young's modulus of 83.7 GPa, ultimate shear strength of 673 MPa, shear modulus of 30.5 GPa, and a fatigue strength limit of 190.2 MPa, as estimated by Basquin's model at 5 x 106 cycles. Fracture analysis indicated that crack nucleation predominantly occurred on the surface under pure torsion loading. In high-cycle fatigue (HCF) tests, cracks propagated at approximately 45° (Mode I), while in low-cycle fatigue (LCF) tests, propagation occurred at around 90° (Mode III). Fracture profiles also revealed significant number of deformation twins and instances of intragranular fracture near the fracture surface.

Resumo em Inglês:

SnO2-based TCO films can decrease the cost of solar cells, but its corresponding ceramic targets are difficult to sintering densification. Therefore, Ta2O5 and ZnO are used to enhance the density and conductivity of targets. The targets have rutile phase structure, dense microstructure and fine grains. The 0.85 wt% ZnO and 3 wt% Ta2O5 doped target sintered at 1500 °C achieve high relative density (>99%) and low resistance (< 50 Ω). The as-designed targets contribute to depositing SnO2-based TCO films by magnetron sputtering.

Resumo em Inglês:

The present study aimed to analyze the effects of the anodization process and addition of silver nanoparticles by sealing process on corrosion resistance and biofilm formation in titanium. For this purpose, CP grade 2 titanium samples were pickled and anodized in Psidium Guajava-based electrolyte, in galvanostatic mode with the application of 0.1 mA/cm2 for 300 s. For the incorporation of silver nanoparticles, the sealing process was used. The sealing of the anodized samples was performed in sodium carbonate solution without and with the addition of 0.25, 0.5, 1 and 2 mM AgNO3, for 30 minutes at a temperature of 75 ºC. The samples were characterized regarding their morphology by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and atomic force microscopy (AFM), corrosion resistance by potentiodynamic polarization, and bactericidal action by optical density microtiteration. The anodizing process resulted in the formation of an oxide layer (TiO2), with greater surface roughness and better anticorrosive performance, compared to pure titanium. The sealing process proved to be effective for incorporating silver into the anodized titanium surface, at all concentrations evaluated, inhibiting the proliferation of Escherichia coli and Staphylococcus aureus bacteria, favoring the bactericidal effect.

Resumo em Inglês:

Silica gel was synthesized from rice husk silicate, a sustainable feedstock, and functionalized with Ag, Cu, and ZnO nanoparticles to evaluate the liquid absorption capacity of these nanocomposites and their potential use in active packaging. From a two-level full factorial experiment, where pH, silicate modulus and SiO2 concentration were tested, silicas with varied surface areas (250-750 m2/g) and pore volume (0.4-1.0 cm3/g) were obtained. The silica with the highest porosity (1.0 cm3/g) was synthesized from a solution containing silicate with a modulus of 2.0 and a SiO2 concentration of 20 g/L, by acidification to pH 6. The product obtained showed the highest absorption of water and simulated body fluid (190%) and was chosen as the matrix for functionalization with nanoparticles produced from chemical reduction (Cu, Ag) and precipitation (ZnO) methods. The incorporation of ZnO nanoparticles into the silica matrix had an additional contribution to liquid absorption, at a rate of 0.04%/ppm.

Resumo em Inglês:

This study investigated the mechanical and anti-corrosive properties of two graphene derivatives multi-layer coatings applied to a superelastic NiTi alloy. Several aspects of the coating process and electrochemical characterization remain unclear, including the impact of a multilayer during dip-coating on the final morphology and corrosion resistance of the system. Additionally, the relationship between long-term immersion tests, mechanical cycling and the anti-corrosion performance of these coatings requires further investigation. The coatings were formulated with GO and rGO dispersed in SEBS to be deposited as flexible nanometer films on NiTi wires using the dip-coating technique. The coating characterization was conducted through scanning electron microscopy, atomic force microscopy, X-ray diffraction and energy dispersive scattering. The mechanical performance under superelastic loading-unloading cycles was evaluated using uniaxial tensile tests. Potentiodynamic polarization and electrochemical impedance spectroscopy analyses were employed to assess corrosion. The potentiodynamic polarization results demonstrated an enhancement in corrosion resistance for the coated samples, particularly in specimens coated with rGO. Additionally, electrochemical impedance spectroscopy analysis revealed superior performance of the coating containing GO after 21 days of immersion in a simulated body fluid. These findings represent an advancement in the investigation of the NiTi surface modification by graphene derivatives.

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The Fe-8.2wt.%Cr-0.6wt.%C-Xwt.%Nb surfacing alloys were successfully applied to the substrate of 60CrMnMo steel through the submerged arc surfacing process utilizing a flux-cored welding wire. This study systematically explores the influence of niobium content on the microstructure and properties of these alloys, and delves into the underlying mechanisms. The results show that the microstructure of the surfacing alloy is mainly composed of γ-Fe, α'-Fe, NbC, and Fe-Cr phases. As the niobium content in the surfacing alloy was increased from 0.06% to 4%, the morphology of NbC transitioned from dispersed particles within the matrix to short rod-like structures concentrated at grain boundaries, accompanied by a refinement of the martensite structure. The hardness of the surfacing alloy exhibited an increase of 28%, while its wear rate was halved, resulting in a twofold enhancement in wear resistance. Under identical wear conditions, the wear rate of the experimental 60CrMnMo steel plate was found to be 125 times greater than that of the 4 wt.% Nb surfacing alloy, indicating a significant improvement in wear resistance for this latter alloy. This improvement can be attributed to the rich presence of rod-like NbC in the 4 wt.% Nb surfacing alloy, which is deeply embedded in the martensite matrix and effectively enhances the material, thereby jointly improving overall wear resistance.

Resumo em Inglês:

This study developed a bone cement based on hydroxyapatite (HAp) and magnetically activated with cobalt ferrite (CoFe2O4) and magnetite (Fe3O4) nanoparticles for potential use in orthopedic surgeries like vertebroplasty. Magnetic nanoparticles (MNPs@SiO2) were mixed with HAp in varying ratios (30:70, 50:50, 70:30) and incorporated into a hydrogel matrix of carboxymethylcellulose, glycerin, and distilled water, forming fluid-viscous magnetic cements. These were analyzed through XRD, SEM, swelling degree, pH, setting time, mechanical strength, magnetic properties, and cell viability. XRD confirmed the crystalline phases of each component, while SEM revealed hybrid morphologies with micropores. Cements with higher HAp content exhibited greater swelling in simulated body fluid (SBF) and faster reaction kinetics, with swelling values between 58% and 91%. After 7 days in SBF, the pH stabilized between 7.0 and 7.3, ensuring biocompatibility. Setting times ranged from 12 to 25 minutes, making them suitable for clinical use. Compressive strengths of 28.91 MPa and 30.06 MPa were achieved after 14 days, indicating structural stability. Ferrimagnetic behavior was observed, with magnetizations reaching 27.30 emu/g for magnetite and 31.08 emu/g for cobalt ferrite. All formulations exhibited non-cytotoxic behavior, confirming their safety for biomedical applications.

Resumo em Inglês:

In this study, Al2O3-based ceramics were obtained by 3D extrusion printing using an ink containing carboxymethylcellulose (CMC) and polyethyleneimine (PEI) as additives. The-ceramic pieces were printed using syringes with nozzles of either 0.25 mm or 0.41 mm diameter at a printing speed of 10 mm/s. After drying, the samples were sintered at 1600 °C for 2 hours and characterized for relative density, microstructure, and crystalline phases. The mechanical properties, including Vickers hardness and fracture toughness, were also evaluated. After sintering, groups of samples were re-sintered at 1610 °C with an isothermal plateau of 0 h, 2 h, or 6 h and then characterized. A group of Al2O3 samples, the control group, was processed conventionally (uniaxial pressing→sintering at 1600 °C for 2 hours) for comparative analysis. The results indicate that, under all manufacturing conditions, α-Al2O3 was the only crystalline phase observed. Additionally, the results showed improvements in the mechanical properties of the samples printed by Robocasting after the re-sintering process, regardless of the extrusion nozzle diameter. The relative density increased from 95.3 ±0.4% to 97.4 ±0.3%, Vickers hardness improved from 1322 ±62 HV to 1526 ±45 HV, and fracture toughness increased from 2.3 ±0.4 MPa.m1/2 to 3.2 ±0.6 MPa.m1/2.

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In this study, we explored the effects of etching on the surface properties and tribological performance of silicone rubber for hydrogen compressor applications. Ceramic particle-coated silicone rubber specimens were etched using a solution of nitric acid and ammonium fluoride for different durations. XRD and Raman analyses confirmed that the etching process did not alter the crystalline structure and molecular bonding of the PDMS matrix. EDS analysis revealed changes in surface composition after etching. The findings demonstrated that extended etching times resulted in the formation of complex surface structures, profoundly modifying the topography and wettability of silicone rubber. These surface alterations influenced the interfacial adhesion with ceramic coatings. However, prolonged etching reduced the optical transparency. Compared to bare PDMS, the ceramic-coated specimens showed enhanced wear resistance. Tribological investigations revealed an initial increase in the friction coefficient with increasing etching duration, followed by a slight decrease for the 30-minute etched specimen. Wear analysis indicated that longer etching times resulted in more severe wear tracks, implying increased surface damage and material loss.

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Semiconductors films have many applications, energy conversion is one of the main ones. Oxides are often the material used to fabricate these films. Electrophoresis technique can deposit oxides semiconductors at different voltages and time. Films of zinc oxide (ZnO) were electrodeposited on conductive glass, adding weight percentage of tin chloride to improve its photo catalytic properties. The films and cells were characterized by X-ray, UV-Vis and EIS. The characterization showed that higher voltage decreased the band gap value from 3.3 to 3.26 eV, below the average for pure zinc oxide, around 3.30. The films acted as photoanodes in solar cells, with maximum current density of 2.88 mA/cm2 and open circuit of 0.68 V. The synthesis method was efficient and can be used for further reseach into semiconductors’ films and be applied for membranes, photoanodes and other applications.

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Zirconia woodpile scaffolds (3Y-TZP/PL, n = 20), designed with null inter-filament spacing, were manufactured using the Direct Ink Writing (DIW), an extrusion 3D printing technique. A ceramic ink containing 40%v/v 3Y-TZP powder, 59%v/v PEG (Polyethylene glycol)/Laponite ink, and 1%v/v DBP (Dibutylphthalate) was used. For 3D printing, we used Ø 0.63 mm nozzles, a printing speed of 10 mm/s, a cross-layer deposition strategy, and no air gaps between filaments. The scaffolds were sintered at 1550 °C for 2 h. The mechanical characterization involved measurements of X-ray diffraction, scanning electron microscopy, Vickers microhardness, Vickers nanohardness, and modulus of elasticity and compressive strength. The sintered samples showed predominantly the ZrO2-tetragonal phase and a microstructure characterized by a bimodal distribution of grain sizes. The samples had a relative density of 90.1 ±1.5%, a Vickers microhardness of 1172 ±45 HV, a Vickers nanohardness of 1608 ±78 HV, a modulus of elasticity of 203 ±16 GPa, and a compressive strength of 192 ±54 MPa. The results showed that DIW processing followed by proper sintering is a promising method for making zirconia scaffolds for biomedical applications.

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This research examines the effect of thermal power plant desulfurization by-products on pipeline carbon steel alloy corrosion dynamics in soil aqueous solutions to improve soil properties and decrease carbon steel pipeline corrosion rates. Electrochemical tests such as chronopotentiometry, potentiostatic polarization, and electrochemical impedance spectroscopy (EIS) assessed corrosion behavior. Adding desulfurization by-products to soil solutions (DBS) created a transpassive layer during potentiostatic polarization, with a passive current density of about 10μA.cm-2. EIS measurements showed a substantial increase in polarization resistance, with the DBS exhibiting nearly 700 times higher resistance than the standard soil solution (SSS) at 0V (OCP). Raman spectroscopy identified lepidocrocite (γ−FeOOH) in the DBS-treated coupons, while maghemite and akaganeite were found in chloride-enriched conditions.AFM analysis indicated heightened surface roughness with DBS addition, especially with NaCl. XRF and FTIR spectroscopy of the waste products identified them as primarily composed of silica, aluminosilicates, and oxides of calcium, magnesium, and aluminum. The results elucidate DBS's impact on soil corrosion and suggest methods to mitigate corrosion in industrial and environmental contexts. This study enhances the understanding of buried pipeline corrosion mechanisms and presents a new use of thermal power plant waste for corrosion protection.

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Polyhydroxybutyrate (PHB) is a crystalline and linear biopolymer that is biodegradable and biocompatible. However, due to its high crystallinity, PHB is rigid and brittle, limiting its applications. The brittleness of PHB can be reduced by incorporating reinforcing fillers. In this context, this study aimed to produce biodegradable composites based on a PHB matrix and mica, as a filler. Scanning electron microscopy (SEM) revealed the lamellar structure of mica within the PHB matrix. Fourier-transform infrared spectroscopy (FTIR) confirmed characteristic mica vibrations, while X-ray diffraction (XRD) identified crystalline phases from both PHB and the filler. Differential scanning calorimetry (DSC) demonstrated mica’s effect on crystallinity. Thermogravimetric analysis (TGA/DTG) showed increased thermal stability, with Tonset rising from 144 °C (pure PHB) to 212 °C (PHB/mica 12%) and Tmax from 207 °C to 260 °C. Tensile testing indicated reduced stiffness, from 413 MPa (pure PHB) to 333 MPa (PHB/mica 12%). These findings highlight mica’s role in modifying PHB’s structural, thermal, and mechanical properties, addressing gaps in the literature regarding this composite system.

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In this research study, Aluminium-based alloy (AA6092) reinforced with 3 wt.% Boron Carbide (B4C) and 5 wt.% Zirconium dioxide (ZrO2) particulates was fabricated into Aluminium Metal Matrix Hybrid Composites (AMMHCs) via stir casting. These AMMHCs were subsequently friction-stir welded under various conditions to optimize the ultimate tensile strength (UTS) and weld nugget hardness (WNH) of the welded joints. This innovative AMMHC material is replacing the AA6061, and AA6082 composites for the applications like bulkhead partitions in ship hulls since this AMMHC has superior properties such as reduced weight, enhanced specific strength, and lower thermal expansion coefficient. To optimize the performance of friction stir welded butt joints in AA6092/3% B4C/5% ZrO2 composites, key Friction Stir Welding (FSW) process parameters including Tool Rotational Speed (TRS), Welding Speed (WS), Axial Load (AL) and Tool Tilt Angle (TTA) were examined. In this research work, empirical relationships were established between the most influential parameters (TRS, WS, and AL) and the resulting responses (UTS and WNH). A desirability function approach was employed to predict optimal values for UTS and WNH, leading to recommended process parameters of 1279.18 rpm for TRS, 53.54 mm/min for WS, and 4.9 kN for AL and TTA for 1.5°. The calculated UTS, and WNH values of 513.09 MPa and 194.92 HRB, respectively, were subsequently validated through experimental verification.

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Metallic cobalt is valued for its thermal and corrosion resistance. In 2018, cobalt prices surged to 95,250 USD/t, fueled by the growing electric vehicle market. However, metallurgical challenges persist, including cost reduction and impurity control. Manganese, a frequent impurity in cobalt electrowinning from laterite and copper ores, can reach up to 560.6 mg·L−1 in leach solutions. Though solvent extraction removes ~90% of manganese, residual amounts impact current efficiency (CE), specific energy consumption (SEC), and deposit quality. Electrowinning tests at 200 A·m−2, 60°C, and pH 4 showed that 0.12 g·L−1 Mn2+ increased CE to 92.2% but raised SEC to 1.96 kWh·kg−1. Mn2+ altered deposit morphology, reducing microhardness and increasing brittleness. Thermogravimetric analysis revealed ~1.35% mass loss in deposits with Mn2+, while higher concentrations enhanced residual strain and enlarged crystallite sizes. Deposits exhibited primarily hexagonal close-packed (HCP) structures with occasional face-centered cubic (FCC) phases.

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Homogeneous and stable ceramic suspensions with high solids loading and low viscosity pose a significant challenge in vat photopolymerization additive manufacturing, once solid particles tend to increase viscosity. Instead, organic materials can contribute to decrease viscosity and post-sintering shrinkage. A base suspension was formulated using PEGDA along with dispersant DISPERBYK-111 (3 wt.% of the monomer powder), zirconia powder (40 vol.%), n-methyl-2-pyrrolidone (10% vol.), and a photoinitiator (2 wt.% of the monomer). The introduction of 10 vol.% solvent resulted in a 22.6% reduction in the suspension viscosity. The average post-sintering shrinkage measured 26.11% across all three dimensions. Sintered components exhibited an average density of 5.95 g/cm3 and an average flexural strength of 256 ± 49 MPa. Additionally, the parts demonstrated anisotropic tribological behavior, low porosity and low surface roughness for polished (Ra 0.032) and untreated (Ra 0.33) surfaces. It was concluded that incorporating minimal amount of solvent into ceramic suspensions does not adversely affect their rheological and mechanical properties, while ensuring satisfactory surface quality of the sintered components.

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AA6060 aluminum is an alloy widely used in the electrical and marine industries. However, its corrosion resistance can be compromised in certain aggressive environments. This study examines the combined effect of magnetic field and imposed potential on the corrosion of AA6060 aluminum wire in seawater. Electrochemical tests and surface analyses were carried out in free immersion, in the presence of a magnetic field, under an imposed potential, and in the simultaneous presence of a magnetic field and an imposed potential. The corrosion kinetics and the mechanisms involved were analyzed by mass loss measurements and microscopic observations.

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This study investigates the microstructural and crystallographic changes in a novel Nb-enhanced, Ti-reduced maraging steel. The hot-rolled steel was solution annealed at two different temperatures followed by aging. The Electron Backscatter Diffraction (EBSD) analysis of hot-rolled sample revealed a predominant {112}//RP texture, reoriented to {110}//RP during aging to minimize internal energy and stress. Solution annealing at 820oC followed by aging favored a {111} orientation, resulting in minimal crystallographic defects and grain distortion. In contrast, higher solution annealing temperatures promoted the formation of {001} cleavage planes, increasing brittleness and crystal defects, thereby impacting the material's suitability for high-performance applications.

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Based on the sol-gel titration technology, a novel process method to prepare the ZrO2 beads with the advantages of 130 nm grains and no pores is proposed. These advantages can greatly improve the bead density and hardness, decline the sintering temperature. Furthermore, the proposed method can prepare different types of the beads whose diameters range from 0.1 mm to 0.8 mm, and with uniform size and well spherical type. The density of the bead tested results mainly concentrate on 6.04 g/cm3, and the hardness on 1280 HV. The SEM investigation results illustrate that the bead grains are evenly distributed. The surface and cross section of the bead grains are consistent, no pores exist among the grains of finely polished section. The XRD tested results demonstrate that no monoclinic phase exists in the bead. The bead sintering temperature is only 1250 °C.

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The role of the CTAB concentration (0.0 M, NS; 5x10-4 M, ½CMC; 2x10-3 M, 2CMC) and the residence time on the composition, morphology and magnetic properties for the nickel nanoferrite formation by hydrolytic stripping (33% v/v naphthenic/kerosene) at 200°C were studied. X-ray, SEM/EDS, FTIR, VSM, and ICP/OES were used to characterise solids and solutions. Regardless of the experimental conditions, all samples present nickel spinel ferrite as the only phase, with similar Fe/Ni molar ratio. However, those precipitates in the presence of CTAB show more homogeneous morphology than in its absence. CTAB at high concentration (2CMC) increases the discharge rate, reaching 100% at 40 min; 14.79 nm average size nanoparticles were obtained, with better magnetic properties (Ms=53.02 emu/g and Hc=35.59 Oe) than those achieved at low concentration (½CMC) and in the absence of CTAB.

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The optical properties of polyvinyl alcohol (PVA) doped with copper chloride II (CuCl2) were studied. The copper chloride was added to polyvinyl alcohol with different concentrations (0, 1, 3, 5, 7, and 12 wt.%). The PVA:CuCl2 films were prepared using the casting techniques. The absorption and transmission spectra have been recorded in the wavelength range (300-800) nm by using UV-VIS spectrophotometer. The fundamental optical parameters such as optical band gap energy, refractive index, extinction coefficient, and dielectric constants have been investigated. Results show that by adding copper chloride to PVA, the optical parameters (refractive index, extinction coefficient, real and imaginary dielectric constant) are increasing with the increase of concentrations of CuCl2 While the optical band gap energy decreases. The single oscillation energy E0 and the dispersion energy Ed were determined by using the Wemple-DiDomenico model. The results show that E0 and Ed values increase with increasing the dopant CuCl2 concentration.

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Amongst numerous traditional coatings to protect internal surfaces, Diamond-Like Carbon (DLC) films attract significant interest from many industries, due to the ability of these coatings to overcome the toxic and/or environmentally unfriendly aspects of some common deposition techniques, especially electroplating. In addition, DLC coatings can be used to reduce corrosion, wear and importantly, abrasion on the inside of components, providing improved efficiency and prolonged lifetime. This work evaluates the performance of hydrogenated and silicon DLC coatings deposited by Plasma-Enhanced Chemical Vapour Deposition (PECVD) on carbon steel in terms of their erosion and electrochemical corrosion resistance. Erosion studies were conducted in a saline solution under different velocities and sand concentrations - modelling the direct impingement of high velocity, sand-laden fluid encountered in multiphase equipment flow. These experiments showed that for all impingement velocities, the Si-DLC exhibited lower mass loss. This coating enhanced integrity against erosion-corrosion acting together under saline environments with sand. The enhanced resistance was attributed to improved ductility of the surface layer, as well as the generation of an effective corrosion barrier which reduced pitting corrosion and suppressed significantly the anodic reaction.

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Graphene is a versatile constituent with many applications in novel materials demanding improved electrical conductivity and mechanical resistance. Another application reported in the literature is its use as a barrier agent to gases, lipids, and water vapor, due to its honeycomb basal structure. We report on a straightforward method to achieve the surface modification of different substrates by depositing a graphene dispersion. The graphene dispersion in N-methyl-2-pyrrolidone (NMP) was prepared by liquid-phase mechanical exfoliation of graphite flakes and characterized to be comprised by multilayer graphene (mG). Ordinary commercial substrates, films produced by the packaging industry, such as low-density polyethylene (LDPE), poly(ethylene terephthalate) (PET), paper, and cellophane (CEL) were treated by a mG dispersion using drip casting. Scanning electron microscopy (SEM) was carried out on these different substrates before and after mG coating. LDPE showed irregular mG covering and aggregation, compared to the uniform distribution in PET and cellophane films, that corroborates the results obtained from tape tests. UV-Vis transmittance indicated minimal interference from the graphene layer compared to the uncoated film. The results were discussed taking into account the interplay of the surface energy of the chemical substances involved. The different modified films might work as a barrier packaging films.

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Cellular Automata (CA) are powerful simulation tools that operate through discrete elements and associations. CA undirected neighborhood searches may produce specific grain shapes (e.g., octahedral, cuboctahedral, cubic), but not spherical ones. However, in recrystallization modeling, the spherical shape plays a crucial role. Thus, Hybrid Cellular Automata (HCA) share several properties with CA but operate in both continuous and discrete modes simultaneously. Unlike deterministic CA, HCA enable equiaxial grain growth without the need for additional correction algorithms, generating grains that remain initially spherical until they encounter boundaries. This behavior has been addressed by other simulation techniques, but HCA provide a simple and highly effective alternative. In this work, HCA are described in detail, including their foundational principles, algorithm performance, calibration, and potential results. The findings highlight the capability of HCA for straightforward and accurate recrystallization simulations with equiaxial growth.

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Calcium hexaluminate (CA6) is a refractory material with good thermal properties and intrinsic difficulty in densification.This study explored the use of Cariri Stone residue, a calcium carbonate-rich limestone from Ceará, Brazil, as a precursor for producing refractory ceramics containing this phase. X-ray diffraction and preliminary tests were conducted to determine the optimal conditions for its incorporation into ceramic refractories. The results showed that a mixture of Cariri Stone residue and alumina, with a molar ratio of 0.5 moles of calcium oxide to 6 moles of aluminum oxide, achieved the best formation of CA6 at 1500°C. Specimens calcined at 1400°C exhibited the highest apparent porosity, indicating potential for thermal insulation applications. These findings highlight the feasibility of reusing Cariri Stone residue as a precursor for producing refractory ceramics containing the CA6 phase, offering a sustainable and promising alternative.

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Microplastics from synthetic polymers significantly impact ecosystems and human health, making biodegradable polymers a promising alternative. To enhance their properties, nanofillers have been widely explored. In this study, TiO2 nanoparticles, alone and combined with B8 OMMT clay, were incorporated into a PBAT matrix to improve its functionality for food packaging applications. Results revealed that nanofillers did not significantly alter PBAT’s crystallinity (Xc ≈ 33%) or thermal stability (Tonset ≈ 375 °C), and the nanocomposites exhibited a predominantly intercalated morphology. Furthermore, low concentrations of nanofillers improved matrix uniformity. Contact angle measurements showed increased hydrophilicity in all formulations, with B8 OMMT systems exhibiting the highest hydrophilicity. The mechanical performance of the PBAT/B8/TiO2 systems was more promising in terms of stiffness, with a 44% increase in Young’s modulus for the PBAT/B8/TiO2 0.5% system. However, all PBAT/B8/TiO2 systems exhibited a more pronounced loss of ductility. Water activity (aW) analysis demonstrated that TiO2 alone reduced aW values to 0.50–0.53, which could potentially enhance biosafety, while the addition of B8 OMMT increased aW to 0.69–0.76, potentially increasing susceptibility to microbial growth. Notably, systems with TiO2 alone showed the greatest potential for food packaging applications due to their increased biosafety, thermal stability, and favorable set of properties.

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This study explored the use of natural diatomaceous earth (ND) and brewery waste diatomaceous earth (BWD) as precursors for the synthesis of geopolymeric binders, with a focus on optimizing the developed compositions and analyzing their physico-mechanical and microstructural properties. Geopolymers were synthesized using various precursor combinations, with adjustments to their SiO2/Al2O3 molar ratios. ND exhibited high reactivity as a precursor, yielding compositions with compressive strengths of up to 28.59 MPa after 24 hours of curing and low porosity. This performance was attributed to the formation of an amorphous gel with a high density of Si–O–Si(Al) bonds. In contrast, systems incorporating BWD demonstrated reduced performance due to their elevated SiO2/Al2O3 molar ratio and limited geopolymerization, resulting in the presence of unreacted particles within the final microstructure. Stoichiometric adjustments and mechanical activation were critical in improving the compositions performance and enhancing the reactivity of the BWD residue, enabling the production of geopolymers with compressive strengths reaching 31.34 MPa. These findings emphasize the importance of optimizing both the chemical composition and synthesis processes to advance the development of geopolymeric materials, facilitating novel precursor combinations and the sustainable reutilization of industrial waste.

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The effects of CaO and ZnO as sintering aids on the electrical and thermal properties of Gd-doped CeO2 ceramics were investigated. Different systems of general formulas Gd0.1Ce0.9O1.95 and A0.02Gd0.08Ce0.9O1.94 (where A = Ca and Zn) were obtained by mechanochemistry, with a maximum milling time of 20 h. XRD analysis of synthesized samples revealed pure phases with a fluorite-type structure, derived from the CeO2 cubic system. Heat treatments from 800 to 1500°C enhanced crystallinity and confirmed the formation of the solid solution. SEM studies of samples sintered at 1200 and 1350°C showed similar characteristics across all systems. Both CaO and ZnO improved the materials’ relative density (~95%) at a sintering temperature of 1200 °C. Impedance spectroscopy demonstrated that the sintering aids did not have an adverse effect on ionic conductivity at 650°C, while thermal conductivity tended to decrease as the temperature increased, aligning with density results.

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In this study, SiCp/A357 composites containing 10% SiCp by mass were successfully fabricated using the semi-solid stir casting technique. The investigation focused on the microstructure, interfacial characteristics, and mechanical properties of the SiCp/A357 composites. The experimental findings indicated uniform distribution of SiCp within the matrix, with minimal interfacial reaction at the matrix and SiCp interface. Additionally, the interfacial bonding between SiCp and the matrix was found to be highly robust. The composites achieved an ultimate tensile strength of 233.4 MPa and an elongation of 7.67% prior to heat treatment. Following T6 heat treatment, the tensile strength showed significant improvement, reaching 431.9MPa, while the elongation decreased to 5.7%. The orientation relationship between the matrix and reinforcement was investigated, and first-principles calculations were employed to analyse the interfacial bonding between the reinforcement and the matrix. The simulations confirmed effective bonding, which consistent with the experimental observations.

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In this study, intermetallic particles were successfully dispersed in a copper matrix using mechanical alloying with a low-energy planetary mill. The (Ni,Cu)3Al intermetallic phase was added at 5, 10, and 15 wt% concentrations, with particle sizes ranging from 8 µm to 15 µm. The resulting powders were compacted and sintered at 700°C for 30 minutes in an argon atmosphere. Microstructural characterization was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while surface hardness was evaluated through microhardness testing. XRD analysis confirmed that no new phases were formed and no phase changes occurred during the milling process. The microhardness results showed a notable 20% increase in hardness at 10 wt% of intermetallic reinforcement compared to the base copper material. This improvement is attributed to the uniform dispersion of the intermetallic particles, which enhanced the mechanical properties. However, a decrease in microhardness was observed at 15 wt%, likely due to increased microporosity, which reduced cohesion between copper particles and negatively affected the composite’s performance. These findings suggest that an optimal intermetallic content exists for reinforcing copper via mechanical alloying, with 10 wt% offering the best balance between dispersion, microstructure, and mechanical strength.

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The present paper aims to develop and investigate Ti system alloys with the following weight compositions: Ti-20Ta, Ti-20Ta-10Nb, Ti-20Ta-20Nb, and Ti-20Ta-30Nb. These alloys are intended to contribute to the area of ​​orthopedic implants. To achieve satisfactory results, thermodynamic simulations were performed using THERMOCALC software and molecular orbital theory to predict the crystalline phases of the metals. X-ray fluorescence characterizations, energy-dispersive X-ray spectroscopy, and density measurements were performed to verify the chemical composition of the alloys. The crystal structure was verified by X-ray diffraction, optical, and scanning electron microscopy techniques. Vickers microhardness measurements were performed to verify the influence of the crystalline phases on the metal's bulk hardness. The chemical composition results showed that the produced ingots have good quality, and the density results presented close theoretical and experimental values, indicating good chemical homogeneity. The X-ray diffraction measurements showed the following phases: the Ti-20Ta alloy is of the α” type. The addition of Nb in the alloys promoted the formation of β phases, demonstrating that niobium has β-stabilizing characteristics. Regarding the microhardness values, the Ti-20Ta-10Nb and Ti-20Ta-20Nb alloys presented the same hardness values ​​(~ 298HV); the Ti-20Ta-30Nb composition has a lower hardness value (215HV) due to the formation of the β phase, which has a lower atomic packing factor.

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This work investigates the performance of single-layer superaustenitic stainless steel weld claddings deposited by the GMAW and GMAW-RE processes with Ar-2%O2 and Ar-25%He. The weld bead profile and microstructure were studied through optical and scanning electron microscopy and electron backscattering diffraction techniques. The mechanical properties were evaluated by tension, bending, and microhardness tests, and the corrosion performance was evaluated by potentiodynamic and potentiostatic tests to determine the pitting potential and the critical pitting temperature. The results revealed an austenitic microstructure containing a low fraction of the secondary phases for all conditions. The main difference was the presence of partially diluted zones in deposits obtained with Ar-2%O2 while no evidence was noted for Ar-25%He as a consequence of a shallow and flatter weld bead profile. Although thicknesses higher than 5mm and equivalent mechanical properties were obtained, the cladding deposited by the GMAW-RE process using Ar-25%He was unique showing the desired corrosion performance. These results indicate that single-layer claddings deposited by the GMAW-RE with Ar-25%He have the potential to be a cost-effective alternative to industrial application but supplementary research is still necessary to a definitive conclusion.

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Highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) with vitamin E (VE) as an antioxidant is widely used for joint implants. VE helps resist oxidation but raises concerns about reduced crosslink density and wear performance. This research hypothesized that tea polyphenols (tPPs), such as lipid-soluble epigallocatechin gallate (lsEGCG) and epigallocatechin gallate (EGCG), could prevent the usual decrease in crosslink density caused by VE, thereby enhancing wear performance. The antioxidants were blended with UHMWPE at 0.2 wt% and surface chemically crosslinked using di-cumyl peroxide. The surface properties, including crosslink density, roughness, coefficient of friction, and wear performance, were evaluated in detail. The results showed that lsEGCG and EGCG blended UHMWPE had significantly higher crosslink density compared to VE stabilized UHMWPE, which was 17% lower than virgin UHMWPE. The coefficient of friction increased after crosslinking and was higher in tPPs blended UHMWPE, indicating a highly crosslinked network structure. The wear resistance of surface crosslinked tPPs stabilized UHMWPE was significantly higher than VE-stabilized UHMWPE. Additionally, a substantial number of scratches, furrows, and flakes were observed on the surface of VE-stabilized UHMWPE compared to tPPs stabilized UHMWPE. It was concluded that tPPs are promising alternatives to VE for improving the performance and longevity of UHMWPE-based implants.

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Glued laminated timber (Glulam) is important structural solution. Knowing its mechanical response under repeated forces, a gap in knowledge area, is fundamental to guarantee structures long-term performance. This study aims evaluating Glulam behavior under fatigue, considering excitation frequency (1 and 2Hz); cycles number (NC – six levels) and their interactions. Marupá and Pequiá, tropical species within density range of Brazilian Code NBR 7190-1, were adopted. Adhesive RS-216-M (CASCO ®, Hexion), usual in industry, was chosen. Modulus of elasticity in bending (E), obtained before cyclic forces application, was taken as reference and determined based usual equation. Results indicated slight stiffness decrease after repeated forces on Glulam pieces. E mean presented significant variation (by ANOVA, 95% significance) when NC ranges from 1,000 to 691,200, both frequencies. NC and frequency explained E variations for Marupá; for Pequiá, only NC. Glue lines were evaluated, in function of NC, without problems identified, enabling both species for Glulam manufacture.

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This study investigates the microstructural phenomena involved in the temperature-dependent mechanical properties of the Premium rail steel through tensile tests at various temperatures. Dilatometry and scanning electron microscopy were used to characterize the materials before and after tensile tests at different temperatures. Finite element simulations were carried out to measure the residual stresses based on the experimental data acquired from the previous tests. Results show that the total elongation increases with the temperature, except for the elongation at 500 °C. Microstructural analysis near the fracture region reveals a more pronounced pearlitic contour at this temperature, indicating a mechanical strength reduction process. The fracture surface exhibits brittle cleavage fracture at 100 °C, while ductile fracture is observed at temperatures above 400 °C. Additionally, spheroidized microstructure is found near the fracture surface at 600 °C, suggesting the influence of deformation on the spheroidization process. Furthermore, the microstructure away from the fracture shows spheroidization initiation at 700 °C, indicating that severe plastic deformation considerably reduces the partial austenitization temperature and its consequent cementite spheroidization. These findings provide valuable insights into the temperature-dependent behavior of Premium rail steel, which can aid in its effective use in high-temperature applications.

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This study presents a comparative analysis of two photoanode materials such as bismuth tungstate (Bi2WO6) and zinc oxide (ZnO) for application in dye-sensitized solar cells (DSSCs). The Bi2WO6 and ZnO films were coated onto fluorine-doped tin oxide (FTO) glass substrate via the doctor blade method. The film samples were characterized by using XRD, SEM, TEM, XPS, FT-IR and UV-Vis-NIR techniques. The photovoltaic performance of DSSCs using MO and RhB dyes as sensitizers was assessed under solar light irradiation. Results revealed that Bi2WO6 and ZnO film photoanodes sensitized with MO dye showed superior photovoltaic efficiency compared to when sensitized with RhB dye. Moreover, the ZnO film photoanode achieved an efficiency of 1.24%, outperforming the Bi2WO6 film photoanode which had an efficiency of 0.85% under similar conditions. A probable mechanism for photogenerated electron transfer and charge carrier separation in DSSCs was proposed.

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Diamond-like Carbon (DLC) films demonstrate substantial hardness, minimal friction, and exceptional wear resistance when applied to metal substrates; however, they face challenges related to inadequate adhesion. Furthermore, concerns about thermal stability are prevalent in DLC films, particularly concerning cutting tools, where processing temperatures may reach significant levels. To mitigate these issues, incorporating various dopants and applying multilayer treatments may enhance adhesion, thermal stability, and wear resistance while simultaneously decreasing the coefficient of friction. This study systematically examines the effects of nitrogen and silicon doping on DLC films applied to M2 steel. It employs multilayer treatments to evaluate their influence on wear resistance, employing a fixed ball wear test that monitors wear progression by interrupting the test at various intervals. Plasma treatments, including nitriding, nitrocarburizing, and DLC coatings, were evaluated independently and in combination. A combination of DLC coatings with nitrocarburizing proved to be better for wear resistance when both the coating and the compound layer present a controlled thickness and high hardness, promoting low friction and avoiding debris formation. The findings reveal that Si-doped DLC combined with nitrocarburized layers significantly improves wear resistance and adhesion, highlighting the benefits of integrating duplex treatments with DLC doping to enhance coating performance.

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In order to support new packaging technologies driven by new demands for rapid data communication in 5G and IoT (Internet of Things), as well as prevent issues related to thermal expansion and deformation. Studies aimed at understanding the effect of temperature and time during service life of soldered parts are rare, especially for the Sn/Bi eutectic arrangement. Therefore, this study aims to understand the influence of the aging time (30, 60 and 90 days) at 100 °C on the local eutectic coarsening of Sn-xBi alloys (x=34, 52 and 58 wt.% Bi). Directionally solidified samples, solidified at cooling rates compatible with soldering, were examined using SEM with the aid of Energy-dispersive X-ray spectroscopy analysis, and Vickers hardness tests to assess both untreated and treated eutectic microstructures. The sample having lower Bi content showed higher coarsening sensitivity over time due to increased Bi flow from the β-Sn phase to the eutectic Bi.

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Micro-nano regenerative rubber represents a significant advancement over traditional regenerative rubber by eliminating the need for polluting chemical agents such as coal tar, asphalt, and regenerators. The performance of composite materials filled with micro-nano regenerative rubber depends critically on the degree of filler dispersion. However, current methods for assessing dispersion rely on subjective visual estimation of electron microscope images, which lack quantitative precision and are prone to human error, especially given the complex distribution of micro-nano particles. This study introduces a novel, automated method for grading the dispersion of micro-nano regenerative rubber fillers in scanning electron microscope (SEM) images, leveraging advanced image processing techniques. The proposed method automatically identifies and quantifies the dispersion of micro-nano regenerative rubber clusters through particle size and distribution analysis. By establishing objective grading rules for dispersion levels, it provides a reliable and efficient alternative to traditional subjective assessments. This innovative approach not only enhances the accuracy of dispersion evaluation but also facilitates the development of high-performance composite materials by enabling precise control over filler distribution. The method's effectiveness is validated through comprehensive experimental analysis, demonstrating its potential to significantly improve the quality and consistency of micro-nano regenerative rubber applications in various industries.

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The Ti-6Al-4V alloy is widely used in aerospace components due to its high strength-to-weight ratio and favorable combination of properties, including low density, mechanical strength, corrosion resistance, and creep resistance. However the alloy loses strength and stability above 500°C due to oxidation. To enhance performance and increase its lifespan or working temperature, thermal barrier coat (TBC) is applied. The TBC consists of a substrate, metallic bond coat (BC), thermally grown oxide layer (TGO), and ceramic top coat (TC). The objective of this work was to study the creep behaviour of Ti-6Al-4V alloy without and with BC (NiCoCrAlY) and TBC (NiCoCrAlY + ZrO2-YO1,5) coatings applied by plasma spraying. Creep tests were performed under constant load conditions at a stress of 125 MPa and temperatures of 500, 600, and 700 °C. The creep parameters were determined, and material characterization by optical microscopy. The results showed that the Ti-6Al-4V alloy with BC and TBC exhibited average increases in creep resistance of 77% and 131%, respectively, compared to the uncoated alloy. These coatings resulted in a reduction in the secondary creep rate and an enhancement in creep lifetime. Microstructural analysis revealed that the delamination of the layers increased with the operating temperature.

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Ceramics composed of (0.1)BaTiO3–(0.9)BaZr0.5Ti0.5O3 have been synthesized to fulfill the specifications required for multilayer ceramic capacitors. This study investigates the influence of various annealing temperatures on the materials' microstructure, optical properties, and dielectric characteristics. Findings indicate that elevated annealing temperatures enhance crystallinity, grain size, dielectric constant, and capacitance. Notably, samples annealed at 800 °C demonstrate high crystallinity, increased grain size, a reduced energy band gap (Eg ≈ 3.50 eV), an optimal dielectric constant of approximately 80,000, and a dielectric loss tangent (tan δ) of about 0.14 at room temperature. The substantial dielectric constant suggests that these capacitors are capable of operating effectively at high temperatures. Furthermore, at a frequency of 100 Hz, capacitance values rise with increasing annealing temperature, reaching approximately 70 µF at 800 °C. These results propose that this material holds significant promise as a candidate for high-temperature multilayer ceramic capacitors.

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The present work examined Cu-Al2O3-Gr composites produced using stir casting and analyzed their mechanical properties. Additionally, the wear performance of these composites was evaluated concerning different reinforcement ratios. Three samples were analysed Pure Copper, 96% Cu, 2% Al2O3, 2% Gr, 95% Cu, 3% Al2O3, 2% Gr and 92% Cu, 3% Al2O3, 5% Gr. The incorporation of Al2O3 and Gr reinforcements significantly enhanced the hardness and tribological properties of these metal composites in comparison to pure copper. The potential enhancements in the lubricating and load-bearing characteristics of graphene in Sample 4, comprising 5% graphene, led to improved performance. An analysis of the microstructure of a worn surface from the study examining the distribution of reinforcement and its correlation with mechanical parameters. Wear studies were conducted under various situations to evaluate tribological performance. The results suggest potential uses of Cu-Al2O3-Gr composites in domains requiring strong abrasive wear resistance and enhanced mechanical properties, aiding in the determination of optimal reinforcing quantities for material development in demanding industrial settings.

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Corrosion of SAE 1020 carbon steel, extensively used in the petrochemical industry, remains a persistent challenge. Replacing toxic chromate-based coatings with sustainable alternatives is equally critical. This study introduces an innovative, environmentally friendly surface modification method using the thermal decomposition of cerium chloride heptahydrate (CeCl3·7H2O) dissolved in the ionic liquid 1-methylimidazolium hydrogen sulfate, a non-toxic solvent not previously used for the deposition of anticorrosion protective coatings. Coatings were calcined at temperatures from 400 to 600 °C. Electrochemical analyses revealed that the coating treated at 550 °C exhibited the highest corrosion resistance, even after prolonged immersion in corrosive media. This outcome was attributed to the formation of a dense, homogeneous, and adherent CeO2 layer. The method proved effective in forming protective CeO2 films, confirming the potential of ionic liquids in producing high-performance anticorrosion coatings. Thus, the developed approach represents a promising and sustainable alternative for corrosion protection in demanding industrial environments, particularly within the oil and gas sector.

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In many industries, challenges arise when welding dissimilar materials using traditional methods, such as fusion welding. These challenges often lead to problems like cracking, phase segregation, and intermetallic formation. To solve these issues, a low-operating-temperature friction stir welding (FSW) technique was employed to fabricate dissimilar stainless steel joints. In this study, AISI 304 and AISI 316 dissimilar butt joints were welded by friction stir welding at different tool rotational speeds of 600 to 900 rpm with a constant welding speed of 40 mm/min and an axial load of 15 kN. AISI 304 was on the retreating side, and AISI 316 was on the advancing side during the welding operation. At a tool rotation speed of 800 rpm, defect-free, dissimilar FSW joints with good mechanical characteristics were achieved. The tensile result indicates that the yield strength of the welded metal is higher than that of both base metals. Similarly, the hardness of the weld metal was higher than those of the base metal. It is due to the microstructural refinement of the weld metal attained by dynamic recrystallization caused by the stirring action of the tool at elevated temperatures. The microstructural results indicate ductile fracture properties. The pitting potential of dissimilar steel joints is less than that of similar AISI 304 and AISI 316 joints. However, it can stand in severe, corrosive environments.

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This study evaluated the effect of thermal processing in hydrogen (H2) and argon (Ar) atmospheres on the physical and microstructural properties of niobium (Nb) powders for electrolytic capacitors. Nb powders were treated at 750 °C, 850 °C and 950 °C with isothermal holds of 60 min and 120 min—samples H2-850-120 and Ar-850-120 denote the H2 and Ar atmospheres—using a heating rate of 10 °C/min. Powders were compacted at 150 MPa and sintered at 1200 °C under H2. XRD confirmed predominant βH phase and minor NbO in H2-treated powders, while Ar-treated samples exhibited stronger NbO reflections. FEG-SEM micrographs showed finer grains and reduced porosity in H2-850-120. These results demonstrate that hydrogen-atmosphere processing yields Nb powders with improved homogeneity, particle size reduction and densification—key attributes for enhanced capacitor performance.

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As-cast Cu-Zn components can be manufactured under a wide range of solidification conditions, reflected in varying cooling rates. While industrial processes are well-established, the relationships between grain size (GS), dendritic spacing (DS), and cooling rates in Cu-Zn alloys remain barely explored. Such knowledge becomes fundamental since these microstructural features significantly influence mechanical properties such as hardness. Under this context, the present study investigates the solidification behavior of a Cu-30 wt.% Zn alloy through a combination of SEM-EDS, optical microscopy, XRD, and CALPHAD (Calculation of Phase Diagrams) computation. Systematic measurements of average GS and DS have been conducted on samples solidified under unidirectional solidification (US) conditions (slow) and centrifugal casting (CC) in Cu molds (rapid cooling). The ratios between GS and DS have been analyzed and correlated with hardness variations as a function of the solidification rates. Additionally, SEM-EDS and CALPHAD analyses elucidate the formation of phases and Zn segregation patterns under varying cooling conditions. Appropriate approaches to compute cooling rates have been used so that ranges from 0.60 to 0.95 K/s, and from 15 to 47 K/s have been determined for US and CC samples respectively. These findings provide valuable insights into the microstructural evolution and mechanical property optimization of cast brass alloys.

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In this study, the development of a bimetallic crosshead produced by additive manufacturing (AM) is discussed, evaluating the joint region between the two metals. The focus was on investigating the metallurgical aspect of this hybrid part, particularly the effect of warm forging at the interface, which combines attributes of two different metal alloys. Fabrication of the crossheads involved metal deposition, resulting in a wear-resistant outer layer using AWS A5.36 E110C-G M welding wire and an inner layer filled with ASTM B221 6060 rolled aluminum. The analyses showed that the intermetallic region had good adhesion properties after warm forging, although excessive formation of iron oxides could compromise the ductility of the joint. The results indicate that, with the formation of intermetallic phases minimized, additive manufacturing makes it possible to create complex high-performance components with customized properties, serving as a guide for evaluating the viability of this approach in further studies.

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The microstructures, tensile properties and corrosion resistance of Mg–7.5Al–2Sn–1Zn (ATZ721) base alloys modified by minor cerium (Ce) additions (0.5, 1.0 and 2.0 wt. %) were investigated. Ce addition leads to the formation of Al4Ce phase, reduces volume fraction of Mg17Al12 phase and refines the microstructures. Tensile tests demonstrated that Ce significantly improved the mechanical properties at room temperature (RT) and 175°C. The alloy with 1.0 wt.% Ce showed superior performance with an ultimate tensile strength (UTS) of 237 MPa, yield strength (YS) of 98 MPa and elongation to failure (Ef) of 16.7% at RT, representing 22%, 17% and 52% improvements over the base alloy, respectively. Corrosion resistance was notably enhanced, with the 1.0 wt.% Ce alloy exhibiting a corrosion rate of 1.8 mm/yr in a 3.5 wt.% NaCl solution, significantly lower than the base alloy’s 8.4 mm/yr.

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Aluminum metal matrix composites (AMMCs) are created by incorporating various ceramic particles into aluminum alloys, offering enhanced mechanical properties and customizable thermal and electrical characteristics. Zirconium dioxide (ZrO2) is particularly valuable due to its excellent fracture toughness, wear resistance, low thermal conductivity, and high resistance to mechanical stress and cracking. Its compatibility with aluminum alloys makes it suitable for applications in medical products, electronic equipment, oxygen sensors, fuel cell membranes, and engine valve seats. Friction Stir Welding (FSW) is an emerging solid-state technique for joining AMMCs reinforced with particulate ceramics, effectively preserving their mechanical properties and reducing defects common in traditional fusion welding. This study aims to develop regression models that predict the Ultimate Tensile Strength (UTS), Percent Elongation (PE), and Weld Nugget Hardness (WNH) of friction stir welded AA6092 composites reinforced with ZrO2 particles. The models will correlate with key FSW parameters, including tool rotational speed (TRS), Welding Speed (WS), Axial Load (AL), and the percentage of ZrO2 reinforcement. Statistical software Design Expert, along with analysis of variance (ANOVA) and Student’s t-test, will be used to validate the developed models. Using Response Surface Methodology and ANOVA, optimized welding conditions were identified as TRS = 1208.09 rpm, WS = 51.5 mm/min, AL = 5.13 kN, and 15 wt.% ZrO2. Under these parameters, the highest mechanical properties achieved were UTS = 494.81 MPa, PE = 8.51%, and WNH = 184.57 HRB. The developed regression models demonstrated high accuracy, with prediction errors below ±5% for all responses. These results confirm the effectiveness of the proposed models and parameters for enhancing the mechanical performance of AA6092/ZrO2 FSW joints.

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In this work, the gelcasting method was used to prepare porous Si3N4 ceramics, using sodium lauryl sulfate and Isobam 110 as foaming and gelling agents, respectively. Samples sintered at different temperatures were characterized by mercury porosimetry, X-ray diffraction, scanning electron microscopy, and compressive strength. The findings demonstrated that the samples had a porosity ranging from 53.6 to 67.21%, featuring a porous structure with interconnected pores with average pore size varying between 89.20 and 158 µm and pore throats of ~0.3-0.5 µm. α-Si3N4, β-Si3N4, CaSiO3, and Ca3SiO5 phases were identified in all porous ceramics. Increased β-Si3N4 content, density, and compressive strength were observed in ceramics sintered at higher temperatures. Even when the samples reached a porosity of 67.21%, the compressive strength remained relatively high, with a value of 59.36 MPa. As a result, the porosity and strength of the porous Si3N4 ceramics were well-balanced due to the efficient use of gelcasting method

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This study investigated the laser powder bed fusion (LPBF) processed AlSi10Mg alloy modified by Sc and C elements, and explored the impact of heat treatment on its microstructure and properties. After solution treatment at 500°C for 3 h followed by aging at 150°C for 6 h, the grain size becomes smaller and more uniform, contributing to enhanced mechanical and corrosion properties. The self-corrosion potential (Ecorr) of alloy reaches -0.6536V, with a self-corrosion current (Icorr) of 3.528×10-7A/cm2, indicating a significant boost in corrosion resistance. The alloy had the highest average hardness (HV 91.7) after a 3h solution treatment at 500°C and a 3h aging treatment at 200°C, which was attributed to the uniform dispersion of the Si phase in the α-Al matrix.​ Atomic force microscopy (AFM) results shew that the surface roughness is minimized after the 500°C+3h solution treatment and 150°C+6h aging treatment, with a Ra value of only 5.17nm. Neutral salt spray testing (SST) in simulated marine environments further validates that optimizing the heat treatment process effectively enhances the corrosion resistance of alloys. Overall, the combined modification of Sc and C, and heat treatment provides an effective approach to improve the performance of AlSi10Mg alloy.

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Medium Mn steels have gained significant attention for their potential to achieve exceptional combinations of strength and ductility through controlled microstructural engineering, and intercritical annealing is recognized as a key processing route to optimize austenite formation and mechanical properties in these alloys. However, the precise relationship between annealing parameters and resulting microstructural evolution in medium Mn steels remains inadequately understood, particularly regarding the optimal conditions for achieving superior mechanical performance. Therefore, this study systematically investigated the microstructural development of 7 wt.% Mn steel during controlled hot-rolling and intercritical annealing to establish processing-structure-property relationships. Hot-rolling produced predominantly lath martensite microstructure with minimal austenite presence. Intercritical annealing was conducted at 700°C and 780°C for 1, 2, and 5 h, resulting in ferrite/martensite and austenite microstructures with austenite content ranging from 10 to 25 wt.%. NbC precipitates were identified after electrochemical extraction. On the other hand, samples annealed at 700°C demonstrated optimal mechanical properties in terms of ultimate tensile strength and elongation, while both hot-rolled samples and those treated at 780°C exhibited brittle behavior with low elongation. These findings establish that intermediate annealing temperatures provide the most favorable microstructural balance for achieving superior mechanical performance in medium Mn steels.

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The present experimental investigation focuses on the phase formation, microstructural patterns, microhardness and 3D porosity for a quaternary Al – 5 wt.% Si – 4 wt.% Cu – 1 wt.% Ni alloy. Through the phase diagram and Thermo-Calc Scheil simulation, one can determine the growth sequence of the phases during the cooling process. With slow cooling curve and its first and second derivatives, one can find both liquidus and solidus temperatures. An approach based on the second derivative curve was adopted to determine the onset of solidification and subsequent phase transformations. These experimental results obtained with slow cooling curves are corroborated by those determined by Thermo-Calc software. An ingot of the quaternary aluminum alloy was produced by upward vertical unidirectional solidification under transient heat extraction conditions. Here, we used a water-cooled system to investigate the thermal parameters effects on the as-cast microstructure, microhardness and 3D porosity. The impacts of solidification thermal conditions on the microstructural patterns, microhardness and porosity formation were presented and discussed. Higher values of solidification thermal parameters and refined as-cast microstructures were key factors acting during solidification, which served to conditions changes in the Vickers microhardness and porosity formation along the casting. The relationship between porosity and cooling rate is presented and discussed from experimental equation, PC = -0.41Ṫ2+2.36Ṫ+2.51. This result indicates that porosity formation is closely connected to the said thermal parameter. With 3D image analysis, the distribution of porosity size in casting can be investigated. For positions close to the water-cooled system, porosity with smaller sizes, were predominant in casting. However, for positions away from the water-cooled system with lower cooling rates, porosity with higher sizes were observed.

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Magnesium (Mg) alloys are widely used in electronics, automotive, and aerospace industries due to their lightweight, high specific strength, and excellent damping properties. Laser welding, with its high energy density and precise heat control, shows great potential in addressing the challenges of welding thin Mg alloy sheets. This study investigates the laser butt welding of 1 mm thick AZ31B Mg alloy sheets, comparing the effects of welding with and without beam oscillation using tools such as super-depth optical microscope (OM) and scanning electron microscope (SEM). Experimental results indicate that beam oscillation significantly improves weld uniformity, refines the microstructure, and reduces welding defects such as porosity. Stress-strain analysis shows that both methods achieve high strength in 1 mm AZ31B laser welding, with fractures occurring at the weld joint. The non-oscillated weld exhibits strength of approximately 76% of the base metal, while the oscillated weld achieves 85%. However, tensile elongation for both welding methods shows significant decrease compared to the base matel. Fracture surface analysis reveals dimples on the fracture surfaces of both the base metal and the welds. However, both welds exhibit porosity, with fewer pores observed in oscillated welds, demonstrating its superiority over non-oscillated welding. These findings confirm that laser beam oscillation is an effective technique for achieving high-quality welding of thin Mg alloy sheets.

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This study investigates the influence of milling parameters and nanosized alumina (Al2O3) reinforcement on the production of AA1100 via high-energy ball milling (HEBM) in a bath of isopropyl alcohol. X-ray Diffraction (XRD), Laser Diffraction (LD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and density measurements were employed to evaluate the effects of varying milling time, ball-to-powder ratio (BPR), and the addition of Al2O3. The powders were compacted and subjected to solid-state sintering, examined by SEM, and Vickers microhardness testing. The milling condition of 240 minutes with a BPR of 9:1 and no reinforcement promoted a balanced energy input and superior performance, yielding a crystallite size of 32 nm, particle size of 13,52 µm, and density of 2.179 g/cm3. The sintered specimen produced from this condition demonstrated the best densification, with an average Vickers microhardness value of 143 HV.

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The growing demand for sustainable energy storage solutions has prompted the exploration of eco-friendly materials for supercapacitor applications. In this study, we present a simple two-step synthesis of nanoscale carbon spheres using a modified Stöber method, employing black wattle tannin extracted from Acacia mearnsii as a carbon precursor, in comparison with the conventional resorcinol precursor. Morphological characterization revealed that highly homogeneous nanoscale spheres were obtained. Physicochemical characterizations indicated that the tannin-derived spheres exhibited residual silica content due to incomplete template removal, which increased series resistance and limited the material's performance. Although inferior to resorcinol-derived spheres, which achieved a specific surface area of 2093 m2g−1, the tannin-derived material still exhibited a high surface area of 457 m2g−1 and a specific capacitance of 66.3 F g−1 in aqueous H2SO4 electrolyte, with well-defined morphology achieved without an activation step. By using an environmentally friendly precursor, we successfully produced a material with a homogeneous and well-defined structure, high surface area, and obtained through a simple two-step process of polymerization and carbonization without additional activation. These findings may open new directions for future research.

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In this work, a low-cost natural mineral material, spodumene is used as novel sintering aids for Li0.25La0.25NbO3 ceramics. Li0.25La0.25NbO3 (LLNO) with improved electrical properties are synthesized by the spodumene-assisted sintering via high temperature solid state method. The effects of spodumene sintering aids on structure, microstructure and electrical properties for LLNO solid electrolyte were investigated by using XRD, SEM and AC-impedance, respectively. LLNO sintered at 1000 °C exhibits a pure perovskite structure while the samples with added spodumene sintering aids contain some impurities. LLNO with 5 wt.% spodumene sintered at 1000 °C presents an ionic conductivity of 4.96 × 10-5 S·cm–1 at 25 °C with an activation energy of 0.32 eV. The conductivity of LLNO-5% spodumene sample is one times magnitude higher than that of pure LLNO. The results indicate that the introduction of spodumene successfully acts as a sintering aid for LLNO ceramic solid electrolytes.

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Understanding interfacial interactions is a key to enhancing composite performance. This study aims to investigate the structural, thermal, and morphological properties of short Diss (Ampelodesmos mauritanicus) fiber (SDF) functionalized with graphene nanoplatelets (GNPs). The diss fibers were first extracted and then alkali-treated with 4% (w/v) NaOH, while the graphene nanoplatelets were sonicated. A functionalized short diss fibers-graphene nanoplatelets (SDFGNPs) was prepared using a simple mixing method. The results clearly demonstrated strong adhesion of graphene to the fiber surface, as confirmed by electron microscope micrographs. This resulted in improved thermal stability of the fibers, as evidenced by Tmax increasing from 343 °C to 353 °C, indicating a marked enhancement in thermal resistance, along with a notable 70.25% reduction in final accumulated weight loss. Furthermore, spectroscopic analysis revealed the absence of any chemical bonding, supporting the hypothesis that graphene nanoplatelets mechanically adhere to the fiber surface.

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Chitosan/collagen hydrogels have gained prominence in biomedical applications due to their biocompatibility and ability to promote tissue regeneration. However, rheological instability may limit their applicability. This study investigated the structural and rheological properties of chitosan/collagen hydrogels (99:1, 97:3, and 95:5%) crosslinked with 0.1% genipin. The samples were characterized by Fourier Transform Infrared Spectroscopy (FTIR), injectability, viscosity, swelling, biodegradation, and blood clotting time. Genipin crosslinking improved structural stability, increased viscosity and extrusion resistance, and provided slower and more predictable mass loss under physiological and enzymatic conditions. The swelling assay showed a progressive reduction in water uptake with increasing collagen content, further accentuated by genipin, suggesting a denser and more stable polymeric network. Additionally, the hydrogels accelerated blood coagulation, reinforcing their potential use as hemostatic agents.

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This study reveals the synergistic mechanism of build direction and heat treatment on the microstructure, mechanical properties, and damage evolution behavior of selective laser melted (SLM) IN718 alloy. The results demonstrated that the mechanical properties of as-deposited alloys exhibited significant directional dependence: the 0°-oriented specimens showed higher tensile strength of 1001 MPa, while the 90°-oriented specimens exhibited superior plasticity with elongation of 19.9%. After heat treatment, microstructural segregation was eliminated, and δ phases precipitated at grain boundaries. The tensile strength of 0°-oriented specimens increased by 37.4%, surpassing the 26.4% enhancement observed in 90°-oriented specimens. Quantitative characterization of damage evolution behavior via nanoindentation technology indicates that the 90°-oriented specimens exhibit slower elastic modulus degradation in the early stage of damage, with a higher critical damage factor than the 0°-oriented specimens.

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This experimental study investigates the microstructural characteristics, density, and mechanical properties of AA 7050 composites incorporating 5 and 15 wt.% Si3N4. These composites were fabricated using a powder metallurgy (P/M) process. The fabrication involved the mechanical milling of AA 7050 and Si3N4 composite powders, followed by a systematic blending, pressing, and sintering procedure. The sintered samples have been characterised using an optical microscope. The fabricated samples are subject to density analysis, Hardness, compressive strength, impact and tensile strength have been experimentally investigated. The optical microscope reveals a uniform distribution of Si3N4 particles and the increase in hardness of AS15 is 43.06% compared to the basic material A0. A 50.08% enhancement in the compressive strength of the AS15 composite compared to the basic material (A0). The AS15 composite exhibits a maximum tensile strength of 230.65 MPa compared to all fabricated alloys and composites. Conversely, the AS15 composite shows a decreased effect strength of up to 9.25J compared to all fabricated composites, attributed to the increased weight percentage of Si3N4, which contributes to crack formation at the particle-matrix interface.

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This study systematically investigates the synergistic effects of saccharin and sodium dodecyl sulfate (SDS) additives on the structural and morphological properties of electrodeposited Ni-Fe coatings. Copper substrates were electroplated in a sulfate-chloride electrolyte under controlled conditions (pH 5.5, 1 A/dm2, 10 min), with saccharin (0–0.5 g/L) and SDS (0–0.9 g/L) concentrations varied to optimize coating performance. Comprehensive characterization via SEM, XRD, and crystallite size analysis revealed that saccharin significantly refines grain structure, achieving minimal crystallite size (25 nm) and optimal surface homogeneity at 0.33 g/L. Conversely, SDS (0.4–0.6 g/L) reduced grain size to 18 nm but induced porosity and roughness at higher concentrations (0.9 g/L) due to hydrogen evolution. XRD analysis further demonstrated that SDS modulates phase homogeneity, suppressing secondary Ni-Fe alloy formation at elevated concentrations. The combined additives promoted (111)-oriented face-centered cubic (FCC) growth, enhancing microstructural integrity. Optimal parameters 0.33 g/L saccharin and 0.4–0.6 g/L SDS yielded coatings with refined grains, reduced internal stresses, and improved corrosion resistance. These results provide critical insights for tailoring high-performance Ni-Fe coatings in magnetic and anti-corrosion applications.

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This study uses an artificial neural network (ANN) model to predict the wear rate and friction coefficient of the magnesium alloy AZ91D, based on experimental data from a pin-on-disc tribometer. The model includes three essential process parameters: sliding velocity (m/s), applied load (kg), and sliding distance (km), in addition to the chamber temperature (°C). A total of 27 experimental designs were devised using a Box-Behnken design. The ANN model was trained utilizing the Bayesian regularization approach with one hidden layer of 10 neurons. The developed ANN models for predicting wear rate and coefficient of friction were used as goal functions in a multi-objective Pareto-based genetic algorithm to maximize tribological performance. The ideal solution indicates a sliding velocity of 2 m/s, a load of 5 kg, a sliding distance of 1.5 km, and a chamber temperature of 143°C, yielding a minimal wear rate of 1.7891 mm3/kg·km and a coefficient of friction of 0.1435. Energy Dispersive Spectroscopy and Scanning Electron Microscopy analyses of worn surfaces show that the wear rate decreases with increasing load and sliding velocity at higher temperatures. The oxide layer that forms at high temperatures enhances wear resistance, even under high loads and sliding speeds.

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The microstructure evolution and mechanical properties of Mg-12Gd-1Zn-0.6Ti-xAl alloys under different heat treatment conditions were studied. The results show that the as-cast Mg-12Gd-1Zn-0.6Ti alloy is composed of the α-Mg matrix and (Mg,Zn)3Gd phase. With the increase of Al element, Mg12Gd(Al,Zn) (18R-LPSO), Al2Gd and Al11Gd3 phases are formed in the microstructure. Following the homogenization process, the phases of (Mg,Zn)3Gd, 18R-LPSO, and a portion of Al11Gd3 undergo a transformation into the more stable Mg12Gd(Al,Zn) (14H-LPSO) phases at elevated temperatures. As the Al content increases from 0 to 0.8wt%, the proportion of 14H-LPSO phase significantly increases. The Al2Gd, 14H-LPSO, and Al11Gd3 phases exhibit excellent high-temperature stability. In the peak-aged alloy, the precipitated β′ phases can effectively suppress substrate slip and cause precipitation hardening, thereby improving strength. The Mg-12Gd-1Zn-0.6Ti-0.8Al alloy subjected to peak aging treatment exhibits a good combination of mechanical properties, with a yield strength of 187 MPa, a tensile strength of 290 MPa, and an elongation of 6.8%.

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This paper introduces a computational tool designed to assist in classifying and predicting in vitro cellular activity using a dataset derived from the roughness, wettability, and surface morphology of titanium dioxide (TiO2) and titanium (Ti) surfaces. Numerous studies compare TiO2/Ti surface treatments to enhance osteoblast cellular activity; however, critical gaps remain in understanding how surface properties influence cellular responses. This research compiles a dataset based on peer-reviewed scientific articles published on academic platforms, focusing on surface characteristics: roughness, contact angle, presence of nanostructures such as nanotubes, and the percentage gain in cellular viability of MC3T3-E1 osteoblasts obtained from MTT assays (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), relative to control samples. Using this data, an Index of Classification of Increased Cell Activity (ICICA) was developed to categorize cellular responses into three levels: low, medium and high. Using the constructed dataset, decision tree algorithms were applied to develop a model capable of predicting cellular viability. Among the tested algorithms, the Random Forest model demonstrates superior performance regarding accuracy and Kappa coefficient. The developed model provides valuable insights to guide the design of new surface treatments regarding surface properties, such as roughness, wettability, and morphology of pure Ti, aiming to improve the cellular viability.

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This study aimed to develop cassava thermoplastic starch (TPS) biopolymers and polymer bionanocomposites with varying concentrations of montmorillonite (MMT) nanoclay and coconut oil (CO) by extrusion. X-ray diffraction indicated intercalated and partially exfoliated structure of nanoclay lamellae in the TPS, forming a polymer bionanocomposite. Colorimetric analyses showed that the color of the materials changed with variations in MMT and CO concentrations. The water absorption test revealed synergism between MMT and CO in reducing the hydrophilic character of the polymer bionanocomposite. Scanning electron microscopy (SEM) showed heterogeneities in the fracture surface morphologies of the biopolymer with CO droplets, absent in the TPS/MMT bionanocomposite. MMT addition destroyed CO droplets, favoring rougher and more uniform surfaces. Mechanical behavior under tensile test showed that MMT and CO improved these properties. TPS/MMT/CO bionanocomposites produced with sustainable materials showed potential for application in the production of films for packaging perishable fruits, such as strawberries, where the effect of reducing senescence and increasing the shelf life of the fruit was observed.

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This work investigates a non-polluting alternative for activation treatment, consisting of using a saturated solution of MgCl2 in methanol. For this research, three types of solar cells were analyzed: without activation treatment, activation with CdCl2 deposited by sublimation in a closed space, and activation with a saturated solution of MgCl2 by immersion. The solar cells were characterized using several techniques: scanning electron microscopy images were analyzed to show how the grains of the CdTe layer changed after the activation treatment; using the data obtained through a solar simulator, improvements were observed in Voc, Jsc, and FF; efficiency η increased from 4.4% without activation to 11.92% when MgCl2 is used and to 7.42% with CdCl2; these results were contrasted through numerical simulation based on SCAPS-1D software. We propose that the CdS/CdTe heterojunction becomes thinner during activation due to diffusion between these films; in this way, the film thickness and doping concentration depend on the activation treatment. Finally, we demonstrate that the device can be activated with MgCl2, achieving a maximum efficiency of 11.92%; with values of 760 mV, 27.02 mA/cm2 and 0.58 of the Voc, Jsc, and FF respectively.

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This study investigates the microstructure and corrosion behavior of WC-NiSi cemented carbide produced by conventional powder metallurgy, with comparative analysis against traditional WC-Co cemented carbide. Microstructural characterization was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) before and after corrosion testing. Electrochemical performance was evaluated in a 3.5 wt.% NaCl solution through open-circuit potential (OCP) measurements, linear potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The WC-NiSi cemented carbide exhibited a microstructure similar to WC-Co, although with a slightly higher porosity and increased presence of binder islands. Electrochemical assessments revealed that the cemented carbide with NiSi binder demonstrated more noble corrosion potentials, reduced current density, and higher overall impedance compared to its Co binder counterpart, indicating enhanced corrosion resistance.

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Fluid catalytic cracking is essential in petroleum refining but generates harmful silica-rich spent catalysts (CR). Agricultural waste, like burned rice husks, produces high-silica ashes (RHA). Both CR and RHA are promising waste-derived adsorbents. Polyurethane foams (PUFs) are ideal for adsorbing pesticides in water due to their multiple binding sites, making them effective supports for retaining various pesticide classes. Bio-based PUF was synthesized and incorporated with 50% CR or RHA by polyol mass. The sorbents were analyzed using X-ray diffraction, scanning electron microscopy, microtomography, thermogravimetric analysis, infrared spectroscopy, and contact angle. Effectiveness of the adsorbents in aqueous systems was evaluated by adsorption efficiency at different pHs (2.0, 7.0, and 12.0) using pesticides mancozeb, glyphosate, and 2,4-dichlorophenoxyacetic acid. In the experiment with mancozeb after 24 hours at pH 2.0 and a concentration of 300 mg L−1, pure PUF-REF obtained an adsorption efficiency of 85% (38.60 mg/g). In the same experiment, PUF loaded with CR achieved 98% (45.98 mg/g) removal of pesticide, while PUF loaded with RHA obtained adsorption efficiency of 62.5% (29.87 mg/g). This work examines the use of petrochemical and agro-industrial wastes as adsorbents for removing organic contaminants from natural waters, highlighting their potential to enhance sustainability and circular economy practices.

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This study developed new Ti-xTa-xNb-xZr (x = 10, 20, and 30 wt.%) alloy systems to identify new metals with low elastic modulus for potential application as orthopedic implants. X-ray diffraction measurements and scanning electron microscopy were used to analyze the structure and microstructure. The energy-dispersive X-ray spectroscopy (EDS) technique was used to analyze the chemical composition and perform chemical mapping. The impulse excitation technique was used to determine the elastic modulus. The results show that the addition of Zr, Ta, and Nb resulted in the formation of the body-centered cubic (β-BCC) crystalline phase, as revealed by the structural and microstructural characterization results, including XRD and SEM. The Ti10Ta10Nb10Zr (TTZN10) alloy had a (hexagonal compact) + β structure, whereas Ti20Ta20Zr20Nb (TTZN20) and Ti30Ta30Zr30Nb (TTZN30) alloys had a full β phase. Elastic modulus measurements were conducted to evaluate the impact of phase composition on elasticity. The TTZN20 alloy was found to have the lowest value of the elastic modulus (40 ± 5 GPa, which is interestingly similar to that of human bone (about 30 GPa). This finding suggests that the TTZN20 alloy holds significant potential for biomedical applications, offering improved mechanical compatibility with bone.

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A series of cadmium-substituted zinc spinel ferrite samples with the formula CdxZn1-xFe2O4 (x = 0.0, 0.1, 0.15, 0.2, and 0.25) was successfully synthesized via the hydrothermal method, using Uncaria gambir extract as a natural capping agent. X-ray diffraction (XRD) analysis revealed the formation of CdxZn1-xFe2O4 with cubic spinel structure in the space group Fd-3m. The crystal structure changed due to Cd doping, with the sample containing 0.25 Cd resulting in the largest crystallite size and the highest lattice constant. The vibrating sample magnetometer (VSM) analysis showed that the prepared materials exhibit paramagnetic behavior, and the saturation magnetization value in range of 1.11 to 4.12 emu/g. Diffuse reflectance spectroscopy (DRS) measurements bandgap energy in range of 1.71 to 1.84 eV in the present of Cd content. All samples exhibited spherical particle shape, with average grain size increasing from 260 to 380 nm as cadmium concentration increased. Furthermore, the LCR meter showed enhanced dielectric behavior, substituting Cd ions and modulation at x= 0.25, which has a maximum dielectric constant (ɛ) of 1834 at a frequency of 50 kHz. The measured results for all samples suggested that CdxZn1-xFe2O4 ferrites are recommended for the energy storage application.

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This research investigates the enhancement of Ni-SiC composite coatings on AISI 1018 steel through pulse reverse electrodeposition, systematically varying the concentration of nano-Silicon Carbide (nano-SiC) at 1%, 2%, 3%, 4%, and 5%. The study aimed to assess the effects of nano-SiC content on the microhardness, corrosion resistance, and wear performance of the composite coatings (NHC1-NHC5). The results showed a clear trend of increasing microhardness with higher nano-SiC concentrations, starting with a baseline hardness of 131 HV for AISI 1018 steel. The highest hardness was achieved with the NHC5 specimen (5% SiC), reflecting a 5.76% increase compared to the NHC4 specimen. X-ray diffraction analysis confirmed the incorporation of nano-SiC into the nickel matrix, with characteristic SiC peaks observed, indicating its presence in the coating. Increasing nano-SiC content significantly improved the corrosion resistance, as the best result was observed in the NHC5 coating that exhibited the lowest corrosion rate and the material loss. Furthermore, the wear performance was significantly improved, with the NHC5 coating showing a 93.12% reduction in specific wear rate and a 62.93% reduction in coefficient of friction compared to the reference material/condition. These findings were also corroborated through microscopic analysis that revealed minimal wear and corrosion damage on the NHC5 specimen. It was shown that higher nano-SiC content significantly enhances the hardness, corrosion, and wear resistance of Ni-SiC composite coatings on AISI 1018 steel.

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Inconel 625 superalloy metal matrix composite reinforced with titanium nitride through powder metallurgy technique is an alternative for improving the mechanical properties of the well-known corrosion-resistant nickel alloy. In this paper, high-energy ball milling (HEBM) produced the TiN-Inconel 625 composite powders in a SPEX-type vibrating mill. The objective was to address the effect of the reinforcement content and milling time on the characteristics of the composite powders for posterior application on laser cladding. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Laser Diffraction (LD), and X-ray diffraction (XRD) characterized the samples. The results showed that HEBM provided an effective method for producing TiN-Inconel 625 composites due to the good integration of TiN reinforcement into the nickel alloy matrix.

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The high-Mn steel with the composition of Fe-27Mn-1Si-0.027C (wt.%) was selected. Two samples with different grain sizes were prepared by hot rolling followed by annealing: one was annealed at 1100°C for 90 minutes after 60% hot rolling, and the other was annealed at 1100°C for 60 minutes after 80% hot rolling. The study focused on the relationship between the microstructural evolution of the low-C high-Mn steel and its tensile and impact properties influenced by the stacking fault energy (SFE) at room and cryogenic temperatures. Through SEM and SEM-EBSD experimental techniques, ε-martensite phase was observed, and its mechanical response was compared under room and cryogenic temperatures. In consequence, the low-C high-Mn steel did not present the TWIP effect, but the TRIP effect (i.e., dislocation slip deformation) was detected due to the presence of ε-martensite formed by mechanical straining, increasing its volumetric fraction as the testing temperature decreased. Even with the negative presence of the ε-manartensite phase, the mechanical properties of the low-C high-Mn steel (i.e., strength, ductility and toughness) at the cryogenic temperature testing were similar to those of commercial cryogenic alloys currently used for low temperature combustible storage applications.

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CdSe deposited onto Al/Al2O3 substrates and partially recoated with Bi2O3 nanosheets are designed as multifunctional electronic devices. The device contains two channels: one formed from Al/Al2O3/CdSe/Pt (ACP) and the other covered with an additional Bi2O3 layer (ACBP). Band diagram analyses of the channels indicate that the conduction bands of CdSe and Bi2O3 are well aligned. Additionally, structural investigations reveal enhanced crystallinity of CdSe on Al/Al2O3 substrates. Both ACP and ACBP channels exhibit resonance-antiresonance (RA) and negative capacitance (NC) effects in the microwave frequency domain. The presence of Bi2O3 nanosheets enhances the RA phenomena and increases the NC effect by more than eightfolds. While ACP channels display low conductance values, ACBP channels demonstrate enhanced conductance by 167 times at 1.26 GHz. Furthermore, when evaluated as microwave antennas in the frequency range of 0.009–6.0 GHz, ACBP channels show that Bi2O3 nanosheets enhance the power reflection of the antennas by more than three orders of magnitude. The antennas exhibit improved transmission and reflection coefficients, increasing from 86.4% to 99.5% and decreasing from 13.6% to 0.5%, respectively, at a carrier frequency of 3.10 GHz. The smart features of the devices make them promising candidates for advanced electronic applications, including 5G/6G technologies.

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This study examines the impact of surface preparation on the corrosion resistance of anodized AA2198-T851 aluminum alloy. Two pretreatment methods were employed: (i) alkaline degreasing in 10 wt.% NaOH at 60 °C followed by de-smutting in 30 vol.% HNO3, and (ii) etching in an oxidizing acidic solution (K3 Smutt-Go, 7 V, 20 °C) intended to remove copper-containing intermetallic particles. Surface preparation methods were analyzed using SEM, FEG-SEM, SEM-EDS, and XPS. Corrosion resistance was tested through EIS, and NSST. All electrochemical tests were conducted in 0.1 mol L−1 NaCl solution, and the NSST followed ASTM B117-16. The findings show that removing intermetallic particles greatly improves the corrosion resistance of TSA-anodized AA2198-T851. Among the tested conditions, the etched samples exhibited superior performance, showing no observable corrosion after 336 hours of salt spray exposure, confirming their enhanced corrosion resistance.

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This research investigated the application of previously treated titica vine fibers (TVFs) as a reinforcing element in bio-based composites, aiming at the development of sustainable materials with better properties. The fibers were modified with calcium lignosulfonate (CaLS), a byproduct of the cellulose industry with potential compatibilizing properties in polymer composites. Surface treatments on natural fibers are essential to improve adhesion between the fibers and the polymer matrix, promoting a more efficient interface in the composite. Furthermore, they can reduce moisture absorption and eliminate impurities, resulting in increased mechanical properties and physical and chemical stability of the final material. Fourier transform infrared spectroscopy (FTIR) analysis confirmed characteristic vibrations of the fiber's main constituents, while X-ray diffraction (XRD) revealed a crystallinity index of 55.16% and a reduced microfibrillar angle (MFA) of 6.61°. The treated fibers exhibited a water absorption rate of 15.28% and a diffusion coefficient of 3.90 (mm2.h−1) x 10−4. Mechanical properties, assessed via Charpy and Izod impact tests, showed maximum absorbed energy values of 58.44 ± 18.31 J/m and 51.26 ± 10.79 J/m, respectively. Scanning electron microscopy (SEM) revealed predominantly brittle fracture behavior. Despite moderate toughness, the treatment effectively reduced MFA, improving fiber structural characteristics.

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The high-strength low-alloy (HSLA) steels present a challenge in balancing mechanical performance, cost and formability. The HSLA steel design involves adjusting the carbon (C) content and incorporating microalloying elements such as niobium (Nb), vanadium (V), titanium (Ti), which contribute through precipitation hardening, solid solution strengthening, and grain refinement. Nb is the primary microalloying element; it enhances tensile properties by refining the austenitic grain size during hot rolling, increasing hardness, and providing strength, usually, via Nb(C,N) or NbC precipitation. The morphology, size, and distribution of these precipitates critically impact the steel’s behavior. Thermo-Mechanical Control Processing (TMCP) further enhances material properties through Nb addition. However, the effectiveness of Nb in the continuous rolling of long products requires thorough evaluation. This study addresses this issue by quantifying and correlating the effect of Nb under conditions different from those of TMCP, evaluating its effect on the grain size, tensile properties, impact energy absorption, and hardness of AISI 4320 steel following conventional rolling. The results indicate that Nb addition between 200 and 500 ppm improves the yield strength by approximately 10%, while the ultimate tensile strength increases by about 6%. The particle size distribution of the precipitates reveals unusual findings regarding the grain refinement capability of Nb.

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This study investigates the optimization of laser cladding parameters to enhance the surface properties of AZ61 magnesium alloy using Inconel 625 powder reinforcement. Due to the alloy’s inherent limitations such as low wear and corrosion resistance, surface modification through laser cladding offers a promising solution for improving functional performance. An L16 orthogonal array based on the Taguchi method facilitated the evaluation of four process parameters namely laser power, scanning speed, powder feed rate, and gas flow rate. The measured responses included microhardness, dilution rate, and wear volume. Analysis of variance and signal-to-noise ratios indicated that laser power significantly influenced microhardness (84.42%), scanning speed affected dilution rate (87.13%), and powder feed rate predominantly impacted wear volume (89.42%). Grey Relational Analysis identified the optimal parameter combination that achieved maximum hardness, minimum wear, and minimal dilution. The optimized settings produced a low prediction error of 1.89% in the grey relational grade. These findings confirm the effectiveness of Grey Relational Analysis based multi-response optimization in enhancing surface quality and wear resistance of magnesium alloys, making the process well-suited for lightweight applications in automotive and aerospace components.

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In this study, an extensive data set was based on existing literature records in order to enable the suitability of several predictive models, from Multiple Linear Regression (MLR) to Neural Networks (NN), to be examined. The main objective was to, through regression analyses, generate model computations to correlate tensile properties (UTS- Ultimate Tensile Strength, YTS – Yield Tensile Strength and EF – Elongation-to-Fracture) to a given alloy composition and microstructural spacing. This investigation led to positive results, as the highest accuracies of the trained modules (in 80% of the database) were found to be above ~82% (UTS and EF) and a maximum of ~98% (YTS), when analyzing the results to a test data set. Overall, using the standard model’s setup, the Random Forest and Decision Tree models showed the highest accuracy results, with 0.958 for YTS, as opposed to 0.907 for MLR. Moreover, Multilayer Perceptron (MLP)-optimized models yielded the best results for each variable, with the highest increases in accuracy (after optimization) associated with the YTS and EF. The present contribution might imply an important milestone towards alloy design research based on data science guidelines to unlock the full potential of former experiments and their extensive set of results.

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In recent decades, much attention has been devoted to polymer nanocomposites due to their superior properties at minimal filler loadings. Among thermoplastics, polyethylene terephthalate (PET) stands out for its widespread use in the packaging industry, with research increasingly focusing on the incorporation of nanofillers such as graphene oxide (GO) to optimize its properties. The current study investigates the mechanical and viscoelastic behavior of PET/GO nanocomposites (0.02 to 0.05 wt.% GO) produced through the melt mixing technique. GO was synthesized via a modified Hummers method and transferred to a sonicated rapeseed oil dispersion prior to processing in a twin-screw extruder. Nanoindentation measurements demonstrated significant enhancements in mechanical properties with increasing GO loading, while rheological analyses revealed a notable reduction in complex viscosity. These findings confirm the dual role of GO as both a reinforcing agent and a processing aid in PET nanocomposites, achieved through a straightforward and potentially scalable processing route.

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Aluminum-based nanocomposites exhibit enhanced mechanical properties along with improved thermal and electrical conductivity. However, incorporating carbon nanotubes (CNTs) into aluminum via gravity die casting remains a challenge. This study investigates the fabrication of aluminum nanocomposites via traditional casting, integrating nickel powder and multi-walled carbon nanotubes (MWCNTs) pre-treated with isopropyl alcohol and hydrogen peroxide to improve particle adhesion to the matrix. The nanostructured compounds were then incorporated into the aluminum matrix via gravity die casting. The results showed that the addition of nickel powder and CNTs refined the grains and promoted significant improvements in electrical and mechanical properties, with increases of 18% and 7%, respectively, for 0.2 wt.% Ni and 0.075 wt.% MWCNTs, when compared with commercial electroconductive aluminum. Consistent increases in hardness and ultimate tensile strength were observed, along with gains in elongation in most compositions. However, occasional reductions in yield strength and elongation indicate that the effects are not universal but depend on composition and CNT dispersion. Overall, the developed nanostructured alloys exhibited superior performance compared with commercial electroconductive aluminum, combining improved electrical and mechanical properties.

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Automobile manufacturers are always looking for materials that may lighten vehicles without sacrificing performance, safety, or fuel economy. In the current study, titanium diboride (TiB2) and graphene oxide (GO) are used to strengthen the Al7055 aluminium alloy, which is used as a matrix. Al7055/TiB2/GO hybrid nanocomposites are made by double stage stir casting and reinforced with 0, 5, and 10% TiB2 and a constant 5% GO. The Al7055/TiB2/GO hybrid composites specimens wear performance is evaluated utilizing sliding distance, sliding speed, and applied load. In these three parameters were improved utilizing Taguchi method, and Analysis of Variance (ANOVA) was used to examine their impact. Furthermore, Classification and Regression Trees (CART) analysis was utilized to assess the relative significance of wear characteristics and forecast wear rates. According to the CART outcomes, the two most important forecasting factors of wear rate are applied load and sliding speed, with applied load accounting for 100% of the accuracy of the model, sliding speed for 80.6%. and sliding distance for 2.3%. In comparison to the Al7055 base matrix, surface morphology study showed reduced degradation because of homogeneous reinforcing distribution of particles and refinement of grains. When compared to the base Al7055 alloy, the wear rate dropped with increasing TiB2 reinforcement and improved with greater applied load and sliding speed. The maximum wear reduction was around 45–55%. The automobile industry uses Al7055/TiB2/GO hybrid nanocomposites to increase strength and reduce their weight.

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Vat photopolymerization via digital light processing (DLP) enables the rapid fabrication of high-resolution ceramic components. However, careful post-processing is required to remove the hardened resin and consolidate the microstructure. Polymer removal can be achieved through chemical dissolution and/or thermal decomposition, though solvent debinding remains scarcely explored for DLP ceramics. This study assessed the efficiency of solvent debinding in alumina specimens produced by DLP, examining the effects of solvent type, specimen geometry, and temperature. Samples with three geometries (varying surface area/volume ratios) were printed from a photocurable suspension containing 40 vol.% solids and poly(ethylene glycol) diacrylate. They were immersed in isopropyl alcohol, acetone, or chloroform at 20, 40, or 60 °C, and polymer removal and porosity evolution were monitored. Chloroform achieved the highest debinding efficiency, though prolonged exposure (>240 min) caused chipping and cracking. The optimal condition, 40 °C for up to 30 min, enabled partial polymer removal while minimizing defects during subsequent heating. Combining solvent debinding with thermal debinding, particularly under N2 flow, further improved densification, yielding defect-free parts with relative densities up to 97%, and enhanced surface finish. Thus, solvent debinding effectively minimized defects, ensured uniform binder removal, and improved the microstructural quality of DLP-fabricated alumina ceramics.

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This study examines the effect of heat treatment at 50 °C on PLA/Wood composites produced by fused deposition modelling (FDM). The material consisted of PLA with 20 wt% recycled pine particles and was printed in two raster orientations (0°/90° and −45°/45°). Annealing was performed at 50 °C for 1 h, below the glass transition region, to promote molecular relaxation at interlayer regions while preserving dimensional stability. After treatment, the void content decreased from ~12.7% to ~11.4%, and Shore D hardness increased by ~2%. Tensile strength rose from 17.83 to 28.95 MPa (0°/90°) and from 16.55 to 27.58 MPa (−45°/45°). Flexural strength increased by up to 48%, and Charpy impact resistance increased from 34.36 to 48.86 kJ/m2 (0°/90°) and from 42.23 to 54.38 kJ/m2 (−45°/45°). Microscopy indicated reduced interlayer separation and more cohesive fracture paths after annealing. The results show that heat treatment at 50 °C improves mechanical performance in PLA/Wood without altering external geometry or compromising the bio-based reinforcement.

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In this study, the feasibility of using Selective Laser Melting (SLM) fabricated high entropy alloy reinforced aluminium matrix composites (AMCs) as a new class of advanced materials for high-performance applications will be investigated. In addition to the comprehensive review and case study analysis, a predictive framework that elucidates the relationship between SLM process parameters, microstructural evolution, mechanical property improvement and applicability is proposed. Moreover, a published data meta-analysis of individual cluster cylinder tests is also obtained to quantitatively compare HEA-reinforced AMCs versus ceramic carbon nanotube-reinforced AMCs. In this paper, based on a new categorisation of fabrication issues into material intrinsic, process-induced, and application-scale issues, we offer a three-step research roadmap from laboratory optimisation to industrial validation. Results show HEA reinforced AMCs can demonstrate better tensile strength, hardness, fatigue and thermal stability. For one, there are challenges of porosity, oxidation, scalability, etc., and for two, opportunities in hybrid reinforcement strategies, process optimisation with AI, and sustainable manufacturing. Thus, this review gives both synthesis and new insights to develop SLM-integrated HEA-reinforced AMCs for future fabrication.