The Influence of Shaping and Pore Formation on the Electrical Properties of Tantalum Powder

High-voltage, high-specific-capacitance tantalum powders for capacitors were prepared using K₂TaF₇ as raw material via a process involving sodium reduction, shaping and pore-forming, high-temperature sintering, and deoxidation. Effects of the shaping and pore-forming treatments on microstructures, pore architecture, and electrical properties of the tantalum powders were systematically investigated. The particle size distribution, morphology and pore structures were characterized using laser diffraction size analysis (LDSA), field-emission scanning electron microscopy (FESEM), and a 3H-2000PS2 static volumetric porosity analyzer. The wet electrical performance of anodes fabricated from the resulting powders was also evaluated. The results demonstrated that the shaping and pore-forming treatments could improves the dispersion of internal agglomerates within the particles. After high-temperature sintering and deoxidation, the treated powders exhibited a reduction in micropores smaller than 1.0 μm, more uniform agglomeration state, and fewer agglomerated clusters. Anode samples sintered from these powders, when anodized at high voltage (above 100 V), can exhibit high specific capacitance, low leakage current and low dissipation factor.