Effects of ZrO2 coating on the strength improvement of 2.5D SiCf/SiO2 composites

In this study, 2.5 dimensional KD-II silicon carbide fiber-reinforced silicon dioxide (2.5D (SiCf/SiO2)) ceramic matrix composites with zirconium dioxide (ZrO2) coating were successfully fabricated by sol gel process. Effects of ZrO2 coating on the flexural strength of the composites were comprehensively investigated. Results showed that the flexural strength of the ZrO2-coated SiCf/SiO2 composites was approximately twice that of composites without coating. Moreover, the strength of the composites tested at 1200 degrees C increased approximately by 12% than that of the samples tested at room temperature. Further, the oxidation behavior of the composites was also investigated at high temperatures corresponding to 1300 and 1500 degrees C, which showed an increase in the bonding strength between SiC fibers and SiO2 matrix. The evolution of microstructure revealed that ZrO2 coating led to an increase in the surface roughness of fibers owing to the effective bonding between fibers and matrix.