Preparation of a double layer SiC coating and its oxidation resistance at 1773 K

• A double layer SiC coating exhibits a good oxidation resistance at 1773 K.
• A C/SiC gradient layer is formed by CVR process.
• A good interface compatibility is achieved between CVR and CVD SiC layers.
• The narrow microcrack has enhanced the effect of self-healing.

A self-healing oxidation resistant coating with a double layer SiC was prepared using a two-step technique by chemical vapor reaction and chemical vapor deposition. It was observed that a good adhesion was built between the inner SiC layer and the outer SiC layer. Compared with single layer SiC coatings, the double layer SiC coatings exhibited a better oxidation resistance. After 24 h static oxidation in the air at 1773 K, no mass loss of double layer SiC coatings was observed but a mass gain of 1.73 mg cm−2. Moreover, a brief discussion has been made on the oxidation resistance mechanism.