Study on grinding removal mechanism and surface quality of graphene toughened ZrB2 ceramic matrix composites

Graphene toughened ZrB2 ceramic matrix composites have excellent properties such as wear resistance, heat resistance, creep resistance, oxidation resistance and so on, making them the ideal materials for hightemperature component production, including aircraft wing leading edges and nose cones. Due to its special structure, the grinding machining mechanism is quite different from that of conventional ceramic materials. To achieve high efficiency and low damage machining of graphene toughened ZrB2 ceramic matrix composite parts, the removal mechanism and surface quality are investigated in this paper. Firstly, the SPH simulation model of graphene toughened ZrB2 ceramic matrix composites with abrasive grain indentation and scratching are established. Then the material removal mechanism under different grinding parameters is analyzed through simulation and experiment, and the toughening mechanism of graphene is comprehensively analyzed. Finally, a single-factor experiment is conducted to analyse the influence of grinding parameters on surface quality. The results show that toughened form of graphene during the grinding process is predominantly focused on crack deflection, graphene pulling out and graphene crack bridging, in which graphene plays a superior toughening effect. It can be found that few cracks will cross the grain boundary and expand to other grains, which reflects the barrier effect of grain boundary on crack propagation. As grinding depth and feeding rate increase, Sa and Sz increase by about 12 % and 30 %, respectively. And a decline in surface quality, and an increased number of internal cracks, a heightened brittle fracture phenomenon. The removal form is transformed from plastic removal to brittle removal. The grinding speed increases, Sa decreased by 16.6 %, Sz decreased by 38.4 %, and material profile height decreased by 38.3 %, the surface quality is improved. The number of cracks decreases, the brittle spalling area of the material gradually decreases, and the removal form changes from brittle removal to plastic removal. This study serves as a valuable guide and reference for the grinding process of graphene toughened ZrB2 ceramic matrix composite parts.