Surface evolution and subsurface damage mechanism in fixed abrasive lapping of Silicon carbide

Fixed abrasive lapping (FAL) is considered a promising technology in ultra-precision manufacturing of various hard and brittle materials due to its advantages, e.g., high finishing efficiency and eco-friendly. In this work, the machining efficiency, material removal depth, and surface roughness in FAL of SiC were investigated through a series of practical experiments. The microscopic morphology of the surface and subsurface of the machined workpiece was examined to analyze the influencing mechanism of the machining parameters on the surface and subsurface state. The effects of the presence of defects induced by sintering of the SiC on the material machinability were discussed. A theoretical model for predicting the maximum subsurface damage depth (SSDd) in FAL is established based on microscopic contact state during the process and indentation fracture mechanics, considering the load and grain size. Theoretical results indicate good consistency with experimental ones in that the maximum SSDd increases with load and grain sizes. A strategy for FAL optimization was provided based on the experimental and numerical results.