Preparation of a graphene interface and its effect on the thermal shock resistance of coated ceramic matrix composites

To address the delamination between environmental barrier coatings (EBCs) and the substrate on silicon carbide fiber-reinforced silicon carbide composites (SiC/SiC) above 1300 °C, this study prepared a reduced graphene oxide (rGO) interface by laser reduction of graphene oxide (GO) to enhance the bonding strength between the coating and the substrate. High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy were used to investigate the effects of laser frequency and scanning speed on the reduced structure of GO. By reasonably regulating the processing parameters, an rGO interface with a uniform structure and good graphitization can be obtained, providing support for the subsequent controllable preparation of graphene-based coatings. GO was reduced using different laser powers, and the surface morphology and changes in elemental content after thermal shock tests were observed by scanning electron microscopy (SEM). The results show that, after thermal shock testing, the EBCs on SiC/SiC composites without an rGO interface undergo large-area delamination from the substrate, and a thermally grown oxide (TGO) layer is present at the coating/substrate interface. In the experimental group treated with a laser power of 21 W, no delamination between the coating and the substrate occurs after thermal shock testing; the coating surface remains relatively intact, and the TGO content at the coating/substrate interface is relatively low. The rGO interface can therefore enhance the thermal shock resistance between EBCs and the substrate in high-temperature environments.