Carbothermic reduction of Ta₂O₅ by Ar plasma arc melting

A Ta metal has been produced by the carbon-reduction of Ta₂O₅ by Ar plasma melting. Concentration change of oxygen and carbon impurities in the Ta metal produced by the carbon-reduction has been also investigated. It was found that a pure Ta metal without Ta₂O₅ and TaC could be obtained when the ratio of carbon and Ta₂O₅(C/Ta₂O₅) was 5.0. Considering only total oxygen and carbon concentrations, the Ta metal with the purity of 99.85% could be obtained at the C/Ta₂O₅ = 5.0. The oxygen concentration in the Ta metal considerably decreased with increasing the C/Ta₂O₅, and the Vickers hardness of the Ta metal decreased down to about 230-240 Hv with the remarkable decrease in the oxygen concentration, which means that the hardness of Ta metal strongly depends on the oxygen concentration.