The Influence of Thermal Processing with H₂ Atmosphere on the Physical Properties and Microstructure for use in Electrolytic Capacitors of Nb

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.

Keywords:
Niobium; thermal process; hydrogenation; particle size; porosity; morphology; capacitors