Influence of iodine concentration on microstructure and oxidation resistance of SiB6–MoSi2 coating deposited by pulse arc discharge deposition

• A SiB6–MoSi2 coating was prepared by pulse arc discharge deposition (PADD).
• The coating can protect C/C composites from oxidation at 1773 K for 168 h.
• Influence of iodine concentration on oxidation resistance was investigated.
• The failure of the oxidation resistant coating was investigated.

To improve the oxidation resistance of carbon/carbon (C/C) composites, a SiB6–MoSi2 coating was prepared by a novel pulse arc discharge deposition (PADD). The influence of iodine concentration on thickness, compactness and oxidation resistance of the multilayer coatings were investigated. Results show that the oxidation resistance of the multilayer coatings was improved with the increase of iodine concentration from 2.0 to 3.0 g L−1. The SiB6–MoSi2 coating prepared at iodine concentration of 3.0 g L−1 can protect C/C composites from oxidation at 1773 K in air for 168 h with a weight loss of 1.98%. The failure of the multilayer coatings is due to the volatilization of the multilayer coatings and the escape of CO and CO2.