Comprehensive investigation into grinding characteristics and damage behavior of Cf/SiC composite modified by picosecond-laser ablating

Abstract

Cf/SiC composite is known as difficult-to-machine materials. This study introduced laser-ablating assisted grinding (LAAG) method, and explored the relationship between processing parameters and surface/subsurface damage behavior of Cf/SiC composite. It was revealed that SiO2 ablation products with a loose structure were formed during picosecond-laser ablating, and the ablated layers showed excellent machinability during grinding. Cf/SiC composite underwent brittle removal during conventional grinding (CG); however, significant ductile fracture and smeared removal appearance were clearly observed on the ground surfaces during LAAG. As the grinding speed increased, the grinding forces during LAAG were further decreased, and the brittle-ductile transformation of the normal fiber became more significant. The increase of feed speed would increase the grinding forces and enhance the brittle removal behavior of Cf/SiC composite. The laser power affected the machined quality through the ablation depth and the ablative transformation, and a smaller laser scanning distance would result in a flatter ground surface. Furthermore, subsurface damage of Cf/SiC composite after LAAG was slight, which primarily displayed as interface debonding and SiC matrix cracking. The grinding chips generated during LAAG were primarily composed of cut fiber-bundle and curled SiC matrix, rather than macro-fractured fiber and matrix with unordered size and shape.