Laser-assisted grinding of RB-SiC composites: Laser ablation behavior and mechanism

Abstract

Laser ablation is an important process during Laser-Assisted Grinding (LAG) of hard and brittle materials. To realize controllable material removal during laser ablation of RB-SiC composites, ablation experiments under different Laser Energy Density (LAED) and LAG experiments are conducted. Evolution rules and mechanism of physical phase, ablation morphology and crack characteristics caused by laser irradiation are investigated. The forces of LAG and Conventional Grinding (CG) are compared. The results show that ablation surface changes from slight oxidation to obvious material removal with LAED increasing, and ablation depth increases gradually. The ablation products change from submicron SiO₂ particles to nanoscale particles and floccule. High LAED promotes SiC decomposition and sublimation, which leads to the increase of C element. The SiC phase forms corrugated shape in recast layer and columnar shape in Heat Affected Zone (HAZ) at 56 J/mm². The cold and heat cycle leads to formation of fishbone crack. For ablation specimen under 30 J/mm², the grinding force can be reduced by a maximum of 39% and brittle damage region is reduced. The material removal and microcrack generated will significantly reduce the hardness and improve machinability, which can promote grinding efficiency.