Boron modified multi-layer MoSi₂-CrSi₂-SiC-Si oxidation protective coating for carbon/carbon composites

Boron modified multi-layer MoSi₂-CrSi₂-SiC-Si coatings were prepared on the surface of carbon/carbon (C/C) composites by three-step pack cementation in argon. The morphology and the element distribution were analyzed by scanning electron microscopy and energy dispersive spectroscopy, respectively. The oxidation resistance and thermal cycling property of the multi-layer coating were investigated. These results indicated that the coatings could protect the C/C composites from oxidation at 1173 K for 200 h or 1773 K for 200 h and endure the thermal cycling for 30 cycles between 1773 K and room temperature. The oxidation resistance of the coating was improved due to the formation of compound glass during oxidation.