ZrB2-SiC as a protective coating for C/SiC composites: Effect of high temperature oxidation on thermal shock property and protection mechanism

• ZrB2-SiC coating was fabricated on the surface of C/SiC composites by slurry method.
• The thermal shock property of ZrB2-SiC coated C/SiC composites was investigated.
• Thermal shock property of C/SiC composites was discussed and compared.
• Effect of high temperature oxidation on thermal shock property and protection mechanism was discussed.

ZrB2-SiC coating was prepared on C/SiC composites surface by slurry method, and then the thermal fatigue behavior of ZrB2-SiC coated C/SiC composites was studied. The composition of the coating layers was characterized by XRD, SEM and EDS. With the thickness was 200 μm, the coating was ZrB2 and SiC. During thermal cycle between 1773 K in air and 373 K in boiling water, the weight of the ZrB2-SiC coated composites decreased lightly. The decrease of the flexural strength during the thermal cycle was primarily due to the debonding of the fiber–matrix interfaces and the oxidation of the coated samples. Compared with the uncoated C/SiC composites, the coating played an important role in enhancing the resistance to the thermal shock.