High temperature crack sealant based on SiO2-B2O3 for SiC coating on carbon–carbon composites

Abstract

Abstract Crack sealant required for an anti-oxidation SiC-coating on C/C composites was investigated with the intention of finding material effective up to approximately 1800 K. As a sealant, B2O3 is known to be effective. However, B2O3 rapidly evaporates at temperatures exceeding 1000 K. Hence, mixtures of SiO2 /B2O3 at various ratios were examined in regard to their high temperature durability. As a result of oxidation tests, pure B2O3 over-coated on a SiC-coated C/C composite was eventually confirmed to exhibit sufficient sealing capability up to 1800 K. This result was shown to be derived by the chemical reaction between B2O3 and SiC. By this reaction, a sufficient amount of SiO2was thickly and uniformly formed on the surface of the SiC coating. Keywords: