Laser-induced oxidation assisted micro milling of spark plasma sintered TiB2-SiC ceramic

Abstract

Abstract In this work, a novel process of laser-induced oxidation assisted micro milling (LOMM) was proposed. TiB2-SiC ceramic with hardness of 24.6 ± 0.8 GPa was prepared by spark plasma sintering and used as the workpiece material. The cutting force, surface quality and tool wear mechanisms were investigated. Under laser irradiation and oxygen assistance, a porous oxide layer and relatively dense sub-layer were formed. The hardness of the sub-layer was found to be 12.8 ± 0.7 GPa which was far lower than that of the substrate. Both the cutting and thrust forces increased with increasing the feed per tooth and depth of cut in micro milling of the sub-layer material. The material removal mechanism was dominated by a transition from ductile to brittle mode as the feed per tooth increased from 0.3 μm/z to 1.2 μm/z. The surface roughness Ra of 46 nm was achieved when the cutting speed, feed per tooth and depth of cut were 31.4 m/min, 0.3 μm/z and 2 μm, respectively. The tool wear mechanism was characterized by the flank wear and coating spalling. As a case study, a micro slot having width of 0.5 mm and aspect ratio of 2 was fabricated by the LOMM. For comparison, the conventional micro milling was also carried out using the same cutting parameters. The surface quality fabricated by LOMM was better than that by the conventional micro milling. The machining efficiency in LOMM was improved by 104% as compared to the conventional micro milling.