A SiCnw/PyC-toughened ZrB2-SiC coating for protecting Si-SiC coated C/C composites against oxidation

A novel ZrB2-SiC ceramic coating reinforced with well-dispersed SiC nanowire/pyrolytic carbon (SiCnw/PyC) core-shell structures was prepared on Si-SiC coated carbon/carbon (C/C) composites by heat treatment, chemical vapor deposition (CVD) and pack cementation. Compared to the ZrB2-SiC coating only toughened by SiC nanowires, the ZrB2-SiC coating with SiCnw/PyC structures shows a better oxidation resistance due to Si in raw materials reacting with PyC to generate dense SiC layer, which leads to an efficient load transfer from coating to SiCnw/PyC structure. The results of thermogravimetric analysis shows that the maximal mass loss of the coated C/C specimen with SiCnw/PyC structures is only 2.20% from 323 K to 1673 K, and its mass loss is only 0.30% after thermal shock between room temperature and 1673 K for 40 times.