The processing properties of photocatalysis assisted magnetorheological polishing based on TiO2–CI composite particles

Abstract

With the development of optoelectronic wafers tend to be high brittleness, high hardness and high chemical stability, a single magnetorheological polishing is difficult to meet the application requirements of optoelectronic wafers. The quality and efficiency of magnetorheological polishing (MRP) of photoelectric wafer can be further improved by electric field assisted polishing or photocatalysis assisted polishing. In this paper, TiO2–CI functional composite particles were synthesized by sol-gel method, and a variety of polishing fluid with magnetic, electric and optical multi field effects were prepared. Silicon wafer and fused silica glass were polished by fixed-point centering polishing method, and the mechanism of photocatalytic assisted magnetorheological polishing (PMRP) was studied by comparing the polishing performance of the polishing fluid under different applied fields. The results show that when the polishing fluids prepared by oil-based liquid, the material removal rate is high under the action of a single magnetic field, but the polishing quality is poor. After polishing for 60 min, the height difference in surface profile ΔRz of fused silica glass is 0.67 μm. When the 2.5 kV/mm electric field is applied, the abrasive distribution can be controlled by electromagnetic composite field, and the stiffness distribution of polishing pad is more uniform, but it will reduce the material removal rate (MRR). Compared with the single magnetic field, the height difference in surface profile ΔRz is reduced by 73.1 % to 0.18 μm under the magnetoelectric compound field, which can obtain a more flattened surface quality. When light field and magnetic field are applied, water-based polishing fluid is used for polishing. Because UV light can induce photocatalytic reaction, the strong oxidation group ·OH generated in the photocatalytic reaction can oxidize the materials of workpiece surface into the lower hardness materials. Therefore, the material removal rate is increased by 249 % to 13.4 mg/h compared with that without light field, and the surface roughness was reduced by 69.32 % to 1.05 nm.