OXIDATION RESISTANT (Mo,W)Si2 COATING FOR SiC-COATED CARBON/CARBON COMPOSITES BY IN SITU FORMATION METHOD

In order to protect carbon/carbon (C/C) composites against oxidation, a (Mo,W)Si2 coating was prepared on the surface of SiC-coated C/C composites by a simple in situ information method using Si, Mo and W as starting materials. The microstructures and oxidation protective ability of the as-received coating were investigated. The results show that the (Mo,W)Si2 outer layer coating containing free Si has a good bonding with SiC inner layer. The as-prepared SiC/(Mo,W)Si2 coating can protect C/C composites from oxidation in air at 1773 K for 252 h with a weight gain of 1.56 wt.%. The excellent oxidation resistant property of the double-layer coating is attributed to its dense microstructure and the formation of the stable glassy SiO2 film on the (Mo,W)Si2 coating surface during its exposure to air at high temperatures.