Particulate-containing glass sealants for carbon-carbon composites Original Research Article

A new coating system to minimise high-temperature oxidation and degradation for CC composites has been examined in both isothermal tests and in cyclic tests after water vapour has been introduced. The coatings used consisted of various multilayers containing CVD boron, CVDSiC, and glasses containing both boron powder and SiC particles. For all coatings investigated, significant improvements in oxidation resistance were observed, with some coatings giving a very high degree of protection after as many as three cycles. Microscopic and analytical studies revealed that there was very little degradation of the underlying CC sample, and that a change in the elemental ratios present in the coating revealed that the oxidation of the SiC particles in SiO2 significantly enhanced the barrier to oxygen penetration to the coating.