Role of microstructure on surface and subsurface damage of sintered silicon carbide during grinding and polishing

Sintered silicon carbide with different microstructures: equiaxed grain (EQ) and elongated grain (EL), were prepared. The role of microstructure on surface and subsurface damage during grinding and polishing was investigated. At the same time, the correlation between microstructure and material removal mechanism was studied. The surface and subsurface damage were observed by atomic force microscope (AFM) and transmission electron microscopy (TEM). More grain pulling-out was found on the polished surface with EQ than that with EL. The degree of grain pulling-out is related to aspect ratio and grain diameter of individual grains. Lateral cracks appeared in subsurface for silicon carbide samples with EQ during grinding and polishing, while only plastic deformation could be observed with EL during polishing. Material removal mechanism was found to change from brittle fracture to plastic deformation for sintered silicon carbide ceramics with EL as machine procedure moved on from grinding to polishing. The research related surface and subsurface damage to the microstructure of SiC ceramics and will provide valuable insights into the material removal mechanism.