Preparation of SiC/SiC-CrSi₂-ZrB₂ bilayer coating on C/C composites by a collaborative design and its oxidation behaviors at 1773 K and 1973 K

Excellent oxidation resistance is crucial for the application of C/C composites at high temperatures. In this work, a SiC/SiC-CrSi₂-ZrB₂ coating was prepared via a collaborative design. The SiC inner coating (∼60 μm) was fabricated by the reaction of the pyrolytic carbon layer with molten silicon, which facilitates the elimination of silicification damage in C/C composites during the pack cementation process. Cr and Zr were uniformly distributed in the outer coating through a predesigned SiC porous framework. The composite coating exhibited a low mass loss of 1.48 % after oxidation for 541 h at 1773 K, attributed to the stable sealing effect of the continuous oxide glass layer on pores and cracks. However, the rapid volatilization of SiO₂ and the violent oxidation are the main reasons for the rapid mass loss of the coating during the oxidation process at 1973 K.