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 degrees C in air for 202 It with a weight loss of 2.87 x 10(-3) g/cm(2). The oxidation weight losses of the coated C/C with time accorded with linear and parabolic rule in the temperature range 400-800 and 13001600 degrees C, respectively, and the corresponding oxidation activation energy of the coated C/C composites are 99.6 and 112 kJ/mol, respectively. (c) 2005 Elsevier B.V. All rights reserved.