Thermodynamic Prediction of TaC CVD Process in TaCl5-C3H6-H2 System

An ultra-high temperature ceramic, tantalum carbide, has received much attention for its favorable characteristics: a superior melting point and chemical compatibility with carbon and other carbides. One drawback is the high temperature erosion of carbon/carbon (C/C) composites. To address this drawback, we deposited TaC on C/C with silicon carbide as an intermediate layer. Prior to the TaC deposition, the TaCl5-C3H6-H-2 system was thermodynamically analyzed with FactSage 6.2 and compared with the TaCl5-CH4-H-2 system. The results confirmed that the TaCl5-C3H6-H-2 system had a more realistic cost and deposition efficiency than TaCl5-CH4-H-2. A dense and uniform TaC layer was successfully deposited under conditions of Ta/C = 0.5, 1200 degrees C and 100 torr. This study verified that the thermodynamic analysis is appropriate as a guide and prerequisite for carbide deposition.