Abstract: In the high speed grinding of silicon carbide ceramics, the grains have a strong impact on the workpiece, the strain rate increases sharply, the complex microstructure of SiC ceramics alters the response to stress wave transmission, and mechanical behavior changes. The physical essence of the effect of strain rate on the material removal mechanism is not clear during high speed grinding process. Hence, the effect of grinding wheel speed on the grinding crack damage were investigated with the experimental and numerical single diamond grinding tests. The experimental results show that the grinding speed has a significant effect on the ground subsurface crack damage when the SiC ceramics removed in brittle mode. With the grinding speed increasing from 20 m/s to 160 m/s, the depth of subsurface crack damage decreases from 12.1 µm to 6 µm. A finite element model based on typical Voronoi tessellation method has been established for diamond grinding polycrystalline SiC ceramics. It is found that ground subsurface damage is mainly microcracks under the chip thickness of 0.3 µm, and the depth of subsurface crack damage decreases sharply from 14.7 µm to 4.6 µm with the increasing grinding speed under the chip thickness of 1 µm. Based on the principles of dislocation and shock wave dynamics, the mechanism of "skin effect" of subsurface crack damage was analyzed. The increasing dislocation density and reflected stress wave by the grain boundaries, leading to the intensity of stress field rapidly dissipated, were recognized as the dominant factors resulting in the "skin effect" of subsurface damage.

Key words: silicon carbide ceramics, subsurface crack damage, grinding speed, skin effect