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.