Functionally gradient ceramic coating for carbon–carbon antioxidation protection

Functionally gradient ceramic coating provides an effective antioxidant protection to carbon/carbon composites at intermediate temperatures (below 1000°C) by the formation of a B2O3 glass from the oxidation of boron phases. The glass flows and seals the cracks to prevent further oxygen penetration. A protection layer based on SiC, B4C and Al8B4C7 phases was obtained by carbon conversion of the composite using a pack cementation process with a powder mixture of the ZrB2–SiC–Al2O3 system.