Thermal shock resistance of TaC/SiC coatings on carbon/ carbon composites by the CVD process

Abstract

Carbon/carbon composites (C / C) have been widely studied in the aerospace field given their excellent thermal shockresistance and specific strength at high temperatures. However, they are associated with the problem of rapid oxidization anddeterioration under normal atmospheric environments. In order to overcome these problems, chemical vapor deposition(CVD) coatings of ultra-high temperature ceramics to C / C have become an important technical step. In this study, TaCcoatings on C / C were carried out by a CFD simulation and a subsequent CVD process. A TaC monolayer and a SiC / TaC/ SiC / TaC multilayer were compared with respect to the degree of thermal shock resistance, accomplished in this case withan arc heater. The TaC monolayer was mostly delaminated on the horizontally oriented carbon fibers, which resulted insharpened carbon fibers and porous Ta2O5 layers. However, the multilayer structure showed a protective vitreous coating dueto the oxidation of the SiC layer, with the inner C / C successfully protected by the porous Ta2O5 layer underneath. It can beconcluded that multilayer coatings of SiC / TaC / SiC / TaC can be more effective for thermal shock and oxidation resistancecapabilities of composites.