Investigating surface wear characteristics of single-crystal SiC based on metal electrochemical corrosion

Abstract

Aiming at the environmental pollution of the polishing solution in chemical mechanical polishing, this study introduces a chemical mechanical polishing technique for single-crystal SiC based on metal electrochemical corrosion. The wear properties of the SiC C-surface, as influenced by different materials on grinding balls (Cu, Fe, Al, and Al2O3), and different solutions (KCl, Na2SO4, Fenton, and H2O), were examined through wear experiments to elucidate the material removal mechanisms involved. The experiments demonstrated that the most significant wear marks, with a peak cross-sectional area of 46.89 μm2, were obtained when the C-face of SiC was ground with Al-paired grinding balls in an Na2SO4 electrolyte solution. Energy dispersive spectroscopy analysis of the wear debris revealed an O elemental content of 11 %, and X-ray photoelectron spectroscopy analysis indicated the existence of SiO2 and Al2O3 oxides. Subsequently, the effects of Na2SO4 solution concentration and pH on the wear pattern of the C-surface were investigated. The largest wear cross-sectional area (approximately 50 μm2) was observed when using an Na2SO4 electrolyte solution with a concentration of 1.25 mol/L at a pH of 9 in an alkaline solution. The proposed mechanism of material removal in single-crystal SiC via metal electrochemical corrosion involves the Al metal acting as a cathode. This causes galvanic coupling corrosion, generating a corrosion current, which subsequently induces oxidation of the SiO2 oxide layer on the anode SiC surface. The oxidized layer is then mechanically removed.