Amorphization and C segregation based surface generation of Reaction-Bonded SiC/Si composites under micro-grinding

• Amorphization of both SiC and Si were identified during micro-grinding.
• C segregation prompts surface fracture and micro-pits formation during micro-grinding.
• Surface roughness was dependent on micro-pits generated during machining process.

Micro-grinding of Reaction-Bonded SiC/Si composites (RB–SiC/Si) were conducted to investigate the surface generation mechanism. The results showed that amorphization occurred for both SiC and Si phases, and C segregation appeared on SiC surface and at the interface of SiC and Si. The surface generation mechanism changed from micro-breaking to smoother surface, but accompanied by formation of many micro-pits at phase boundaries with the decrease of feed rate. It was identified that the material removal mode was closely related to amorphization and C segregation (i.e. amorphization would promote ductile material removal while C segregation would aggravate surface fracture and increase the number of micro-pits). Furthermore, it was found that the distribution of micro-pits corresponded with the random and stochastic properties of diamond grits, and the formation of micro-pits during machining process determined the surface roughness. To explain the mechanism of micro-pits formation, a simple interaction model between diamond grit and workpiece was proposed.