HfB₂-MoSi₂/SiC-Si coating was fabricated via pack cementation (PC) combined with slurry painting (SP) followed by heat treatment, where MoSi₂ was in-situ synthesized from Mo and Si. The microstructure evolution and high-temperature oxidation resistance at 1773 K and 1973 K of the HfB₂-MoSi₂/SiC-Si coated specimens were comparatively studied. The protection mechanism of the coating was investigated, based on the structure and thermodynamic transformation of the oxide scale. The results revealed that the HfB₂-MoSi₂/SiC-Si coating possessed better oxidation resistance at 1973 K than that at 1773 K, mainly due to the changed properties of the multiphase Hf-Si-O oxide scale. At 1973 K, the formed Hf-Si-O oxide scale has low oxygen permeability, superior high-temperature stability and self-healing ability. While the Hf-Si-O oxide scale formed at 1773 K is loose, which caused oxygen penetrating into the inner layer and C/C substrate, finally resulting in a high mass loss. This study can provide valuable information and induce facile method to develop high-temperature environmental barrier coatings for C/C composites.

HfB ₂ -MoSi ₂ / SiC-Si涂层是通过组装胶结（PC）与泥浆涂漆（SP）并随后进行热处理而制成的，其中MoSi ₂由Mo和Si原位合成。比较研究了HfB ₂ -MoSi ₂ / SiC-Si涂层试样在1773 K和1973 K时的组织演变和高温抗氧化性能。基于氧化皮的结构和热力学转化，研究了涂层的保护机理。结果表明，HfB ₂ -MoSi ₂/ SiC-Si涂层在1973 K处比在1773 K处具有更好的抗氧化性，这主要是由于多相Hf-Si-O氧化皮的性能发生了变化。在1973 K时，形成的Hf-Si-O氧化物水垢具有低的氧渗透性，优异的高温稳定性和自愈能力。尽管在1773 K处形成的Hf-Si-O氧化物水垢疏松，这导致氧气渗透到内层和C / C基板中，最终导致大量质量损失。这项研究可以提供有价值的信息，并为开发用于C / C复合材料的高温环境防护涂料提供简便的方法。