Comparison of mechanical behavior after thermal shock according to different substrate and coating methods in the SiC coated C/C fiber reinforced composites

Abstract

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 fabricationtechniques: fiber-rod stacking (RS) and needle punching (NP). Second, each surface of the carbon/carbon composites wascoated with SiC using chemical vapor deposition (CVD) or chemical vapor reaction (CVR) to prevent oxidation in airat high temperatures. We prepared three samples (denoted as RS-CVD, NP-CVR, and NP-CVD based on the combinedmanufacturing and coating methods) and subjected them to 1–6 thermal shock cycles at 1500℃ in air. NP-CVD exhibitedthe highest oxidation resistance, as indicated by the minimal weight loss after thermal cycling. The coating layer of NP-CVDexhibited a higher density than that of NP-CVR, allowing for effective protection of the carbon/carbon composite from hightemperatureoxidation. 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 afterthermal cycling. These results indicate that carbon/carbon substrates prepared using NP and coated using CVD exhibitexcellent thermal and mechanical properties even after thermal cycling in air.