Hydrothermal corrosion behavior of silicon carbide ceramics with prefabricated indentation-induced cracks

The presence of unavoidable microcracks may play a vitally important role in determining the service performance and lifetime of the silicon carbide (SiC) components and parts, and greatly affect the service life under the high-temperature and high-pressure water environment. However, studies on the hydrothermal corrosion behavior with the presence of cracks were rarely reported. In the present work, prefabricated indentation-induced cracks were printed on three SiC samples (solid-phase sintered SiC [SP-SiC], liquid-phase sintered SiC, and chemical vapor deposited SiC) under different applied loads, and the effects of prefabricated cracks on hydrothermal corrosion behavior of the samples in high-temperature water were investigated and compared. The results showed that, with the prefabricated indentation-induced cracks printed under the same applied load, the SP-SiC exhibited the worst hydrothermal corrosion resistance among the three SiC samples studied, in which crack deflection and spalling were easily formed, mainly attributed to the concentrated pores formed around the sintering aid (B + C). These pores formed could be enlarged and lead to accelerated indentation-induced crack propagation under the attack of high-temperature water and also the presence of a high-stress field.