Eliminated siliconization corrosion and improved oxidation resistances of SiC-Si coated C/C composites via a ZrB₂-rich transition layer

A ZrB₂-rich compact transition layer was prepared on the surface of C/C composites by the slurry painting and heating carbonization method. The transition layer can not only eliminate the siliconization corrosion of molten silicon on C/C substrate during the preparation of SiC-Si coating by the pack cementation (PC), but also improve the oxidation resistance of SiC-Si coating. The results show that the bending strength retention of SiC-Si coated C/C sample with ZrB₂-rich compact transition layer increased from 70.6% to 93.4%, pretty closed to the bending strength of the raw C/C composites. Moreover, the mass loss of SiC-Si coated C/C sample with ZrB₂-rich compact transition layer was only 0.09% after suffering 50 thermal cycles between room temperature (RT) and 1773 K. And the coated sample was still in a state of mass gain (1.03%) after oxidation for 342 h in air at 1773 K, indicating it possessed outstanding oxidation resistance.