Oxidation Protective Coating on Carbon/Carbon Composite Prepared by Two-step Processes of Pack Cementation and Sol-gel

A SiC-SiC/TaC coating was prepared on carbon/carbon(C/C) composite by a two-step technique of pack cementation and sol-gel to protect C/C composite from oxidation.The surface and cross-section morphologies and phase composition of the coating was analyzed by SEM and XRD,respectively.The results show that a transitional SiC coating prepared by pack cementation process is a whisker-toughened protective coating and the compact out-coating prepared by sol-gel process can effectively fill the holes between whiskers of SiC coating by pack cementation and thickness of the coating increasing from 4 μm to 8 μm.The coating made by two-step technique exhibites excellent oxidation protective ability.The mass loss percentage of the coated C/C composite is only 2% after oxidation in air at 1000 ℃ for 2 h,which is far lower than pure C/C composite and C/C composite with SiC coating.