Preparation of ZrO2 in SiC coating via hydrothermal method and sintering process onto carbon/carbon composite

Abstract

To reduce the defects in SiC coating, a SiC/ZrO2 composite is prepared and coated onto carbon/carbon composite via hydrothermal method and sintering process. The microstructure, surface morphology, chemical states, and elemental distribution of SiC/ZrO2 coating are analysed with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). In addition, we analyze the tribological behavior of the SiC and SiC/SiC/ZrO2 coatings and the related microstructure. The results show that SiC/ZrO2 coating is composed of SiC phase, ZrO2 phase, carbon phase, and SiO2 phase. EDS results show that Si, C, O, and Zr elements are present in the SiC/ZrO2 coating. Moreover, XPS results show the presence of SiC, ZrO2, and SiO2. According to the SEM image, the coating is dense except for some observable cracks. Notably, specimens with the SiC/ZrO2 coating have smaller, more stable friction coefficients and less weight loss than specimens with the SiC-only coating. The formation of ZrO2 strengthens the SiC coating, while the SiO2 formed in the coating acts as a lubricant and reduces the friction coefficient of the coating.