Thermal Shock Resistance of SiCNW-SiC Coating for Carbon/Carbon Composites Fabricated by Successive Two-Step CVD Process

Abstract

The oxidation protective SiC coating toughened by SiC nanowires was fabricated by two-step chemical vapor deposition (CVD) process using MTS as precursor. First, a random-orientation SiC nanowires network was synthesized by atmospheric pressure chemical vapor deposition (APCVD) on carbon/carbon (C/C) composites with Ni assistant. Second, the SiC nanowires network was infiltrated and enwrapped by SiC coating during low pressure chemical vapor deposition (LPCVD) process. The nanowires could effectively toughen the SiC coating by nanowire pullout, nanowire bridging, micro-crack deflection and good interaction between nanowire and matrix interface. The weight loss of SiCNW-SiC coated C/C composites was 2.38% after 25 times thermal cycling between 1773 K and room temperature, while SiC coated C/C composites was 9.50%. The result of the thermal shock showed that the SiCNW-SiC coating had better thermal shock resistance than SiC coating.