Investigation on the machined surface quality and removal mechanism of SiC_f/SiC composites in ultrasonic-assisted grinding

SiC_f/SiC composites have been applied in numerous fields owing to their excellent out-of-plane properties, impact resistance, and delamination resistance. However, such composites are hard and brittle, and thus result in the formation of defects. In this study, we analyse the removal mechanism of different regions of the SiC_f/SiC composites. Additionally, we investigate the effects of machining variables (spindle speed, feed rate and cutting depth) on the grinding force and surface roughness of SiC_f/SiC composites in conventional grinding (CG) and ultrasonic-assisted grinding (UAG). The composites exhibit damage in the forms of matrix breakage, matrix cracks, fibre fracture, fibre debonding and interfacial debonding. The fibre removal modes in CG and UAG are different. Brittle fracture is the predominant material removal mechanism in CG and UAG. Results show that the grinding force and surface roughness decrease as the spindle speed increases, whereas they increase with the feed rate and cutting depth. Compared with CG, UAG is a more efficient and precise material processing method for reducing the grinding force and improving the machined surface quality. The findings of this study offer meaningful guidelines for improving the grinding process and machining efficiency of SiC_f/SiC composites.