Facile preparation of SiC/ZrB2-SiC-Si coatings on Cf/SiC composites for ultrahigh temperature ablation resistance

A slurry method combined with silicon infiltration has good prospects in preparing ZrB2-SiC coatings yet remains a great challenge due to the unevenly distributed ZrB2 and heavily damaged substrate. Here we develop a SiC/ZrB2-SiC-Si bilayer coating on Cf/SiC by the slurry method and low-temperature silicon infiltration. The dense SiC inner layer promotes the interfacial bonding and inhibits the inward infiltration of Si; meanwhile, the liquid-gas co-existing siliconization restrains the ZrB2 aggregation and growth. The resultant coating presents high interfacial bonding of 15.6MPa, can endure 5 ablation cycles for 600s at 1900 °C. Especially, the coated Cf/SiC has high strength retention of 97.3%.