Preparation and oxidation kinetics mechanism of three-layer multi-layer-coatings-coated carbon/carbon composites

Yttrium silicate coatings with an outer glass sealant for SiC pre-coated carbon/carbon (C/C) composites were prepared by a novel in situ formation method using Si and Y₂O₃ as starting materials in an oxidation atmosphere. The structures of the coatings were characterized by XRD and SEM analyses. Oxidation behavior of the multi-layer-coating-coated C/C composites was investigated. It showed that the as-prepared multi-layer coating could protect C/C composites from oxidation at 1600 °C in air for 202 h with a weight loss of 2.87 × 10^-3g/cm². The oxidation weight losses of the coated C/C with time accorded with linear and parabolic rule in the temperature range 400-800 and 1300-1600 °C, respectively, and the corresponding oxidation activation energy of the coated C/C composites are 99.6 and 112 kJ/mol, respectively.