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

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.