Synthesis and morphology of various carbides in the Ta--C system

Tantalum carbides, i.e., TaC and Ta2C, were readily synthesized by evaporating elemental Ta in the presence of acetylene gas. A high-rate physical-vapor-deposition technique employing the activated-reactive-evaporation process was used. The C/Ta ratio of the TaC deposits was found to increase with increasing C2H2 partial pressure. The hardness of the TaC was 2482 kg/mm2 KHN, which is comparable to the literature values, while the hardness of Ta2C was twice that previously reported. It was found that the morphology changed markedly with deposition temperature