Effect of abrasive grain position patterns on the deformation of 6H-silicon carbide subjected to nano-grinding

A surface machined by nano-grinding is the result of the coupled activities of nano-cutting, nano-extrusion and nano-rubbing by multiple abrasive grains of a grinding wheel. With the aid of large-scale molecular dynamics simulations, this paper used a two-grain model to explore the influence of grain position patterns on the deformation of single crystal 6H-SiC. It was found that regardless of the space location arrangement of the abrasive grains (grain position pattern) and the gap magnitude between the abrasive grains (grain gap), the plastic deformation of 6H-SiC is signified by a thin amorphous layer in the immediate subsurface and dislocations in the deeper subsurface beneath the amorphous layer. However, the defective deformation details, including dislocation distribution and thickness of amorphous layer, vary with the grain position pattern and grain gap due to the different stress and temperature distributions generated during nano-grinding. In addition, under the consecutive pattern below a critical grain gap, both the average forces and surface profiles vary significantly with the grain gap. Under the simultaneous pattern, however, the average forces are mostly constant and the profile grooves are in parallel with each other. The investigation concludes that to achieve a high surface integrity with minimal subsurface damage in 6H-SiC, it is important to use grinding wheels of specific grain position patterns.