In this study, we investigated the effect of thermal cycling on the mechanical properties of silicon carbide (SiC)-coated carbon/carbon composites fabricated using different techniques. First, we prepared carbon/carbon composites using two fabrication techniques: fiber-rod stacking (RS) and needle punching (NP). Second, each surface of the carbon/carbon composites was coated with SiC using chemical vapor deposition (CVD) or chemical vapor reaction (CVR) to prevent oxidation in air at high temperatures. We prepared three samples (denoted as RS-CVD, NP-CVR, and NP-CVD based on the combined manufacturing and coating methods) and subjected them to 1–6 thermal shock cycles at 1500℃ in air. NP-CVD exhibited the highest oxidation resistance, as indicated by the minimal weight loss after thermal cycling. The coating layer of NP-CVD exhibited a higher density than that of NP-CVR, allowing for effective protection of the carbon/carbon composite from high-temperature oxidation. In addition, NP-CVD exhibited excellent mechanical properties, including hardness, elastic modulus, and indentation strength. Furthermore, the sample showed only a slight decrease in hardness and indentation strength after thermal cycling. These results indicate that carbon/carbon substrates prepared using NP and coated using CVD exhibit excellent thermal and mechanical properties even after thermal cycling in air.

Keywords: Carbon-carbon composite, SiC coating, Thermal shock, Mechanical behavior.