Preparation of oxidation protective ZrB2–SiC coating by in-situ reaction method on SiC-coated carbon/carbon composites

Abstract

In order to reduce production cost and effectively improve the oxidation protection ability of the ultra-high temperature ceramics (UHTCs) ZrB2–SiC coating for the SiC-coated carbon/carbon (C/C) composites, a ZrB2–SiC outer coating was prepared by in-situ reaction method on SiC-coated C/C. Instead of costly ZrB2 powder, inexpensive B2O3, ZrO2, Si and C powders were used as raw materials to prepare the outer ZrB2–SiC coating with well-developed microstructures. The ZrB2 and SiC phases in the outer coating were synchronously obtained during the preparation of the coating. The isothermal oxidation behavior of the coated C/C composites at 1773K was investigated. The double-layer ZrB2–SiC/SiC coating could prevent C/C composites from oxidation at 1773K for 550h. During oxidation, a kind of ‘embedding structure’ containing ZrO2 and ZrSiO4 will be formed on the surface of the compound silicate glass layer, which is responsible for the excellent oxidation resistance of the ZrB2–SiC outer coating.