Preparation of tantalum metal powder by magnesium gas reduction of tantalum pentoxide with different initial particle size

Abstract Ta metal is frequently used as a raw material in the production of military hardware and electromagnetic components; therefore, obtaining high-purity tantalum is emerging as an important goal. Here, Ta metal powder was successfully prepared by reduction of Mg gas with tantalum pentoxide (Ta2O5). The reduction behavior was studied kinetically using Ta2O5 with different initial particle sizes (0.3 and 1.2 μm). Reduction temperature varied in the range from 1073 to 1273 K. In the X-ray diffraction patterns of reduced powders, pure Ta peaks appear above 1123 K when using the 0.3 μm initial powder, and at 1173 K when using the 1.2 μm initial powder. With increasing reduction temperature, reduction rates were higher with the use of the 0.3 μm powder than with the coarser 1.2 μm powder. This behavior resulted in different activation energies for Mg-reduction (5.234 and 8.695 kJ/mol for the 0.3 and 1.2 μm powder, respectively). In the powder reduced at 1273 K, the oxygen content was lowered to 0.66 and 0.88 wt% for the 1.2 and 0.3 μm powders, respectively; this is explained by differences in the specific surface area according to particle size.