Experimental research on surface characteristics and subsurface damage behavior of monocrystal sapphire induced by helical micro abrasive tools

Abstract

Sapphire crystals have been widely used in the fields of national defense and optical devices due to good chemical stability and high temperature resistance. In this study, the surface quality, edge fracture characteristic and subsurface damage behavior of sapphire induced by helical micro abrasive tools were experimentally investigated. Effects of geometrical structure of helix micro abrasive tool and process parameters on surface topography, section profile height and surface roughness of sapphire were analyzed. To reveal formation mechanism of subsurface damage of sapphire induced by micro-grinding process, the high temperature chemical corrosion was used to etch sapphire workpiece, and the transformation law of surface morphology and crack layer information with corrosion time were obtained. Besides, effects of geometrical structure of helix micro abrasive tool and process parameters on edge collapse feature and surface fracture length for sapphire crystals were discussed. Furthermore, the ratio of etching surface defect area was put forward to qualitatively the degree of subsurface damage and experimental results indicated that the ratio of etching surface defect area of sapphire was increased with the increase of feed speed and grinding depth. This research can supply a theoretical basis for understanding surface feature and subsurface damage behaviors of monocrystal sapphire involved in micro-grinding process and provide important guidance for high surface quality and low subsurface damage grinding of hard brittle materials.