Effects of grinding parameters on material failure mechanisms of 2D silicon carbide fiber-reinforced silicon carbide composites

The Silicon Carbide Fiber-Reinforced Silicon Carbide (SiCf/SiC) composite is widely used in ultra-hightemperature applications due to its exceptional properties, but its brittleness makes machining, especially grinding, challenging. This study investigates the failure modes of fibers and the matrix during grinding of 2D SiCf/SiC composites under varying process parameters, such as wheel speed, feed rate, grinding depth, and surface structure. The results show that transverse fibers undergo ductile removal, shear fracture, bending fracture, and tensile fracture, while longitudinal fibers primarily experience ductile removal, tensile fracture, and bending fracture and normal fibers mainly exhibit shear and bending fractures. The matrix exhibits ductile, brittle, powdery, and peel-off removal modes. Grinding the woven surface (WS) leads to higher grinding forces and surface roughness than the stacking surface (SS), due to differences in fracture mechanisms. The primary material removal mechanisms of grinding wheel are friction wear and grit breakage, resulting from the high hardness of SiCf/SiC. Increasing wheel speed reduces both grinding force and surface roughness by promoting ductile removal, which is attributed to decreased undeformed chip thickness and enhanced strain toughness. The optimal grinding conditions are high wheel speed and sharp grit on the SS, yielding the best surface quality.