Study on material removal mechanism in ultrasonic chemical assisted polishing of silicon carbide

Abstract

An ultrasonic chemical assisted polishing (UCAP) method exploiting the recombination mechanism of ultrasonic vibration, Fenton oxidation and mechanical impact is proposed for efficient finishing of silicon carbide (SiC). Experiments and theoretical analyses were performed to explore the effect of H2O2 content, FeSO4 content and ultrasonic amplitude on removal rate and surface roughness of UCAP and material removal mechanism. The combined interactions of ultrasonic and Fenton oxidation achieved superior polished efficiency and quality with a 19.51 % improvement in MRR and a 18.3 % increase in Ra compared to MP. This originates from the synergistic effect of oxidation of OH generated by chemical polishing slurry and the promotion of mechanical removal of abrasives and oxidation rate of SiC by ultrasonic vibration. Excessive FeSO4 and insufficient H2O2 can induce flocculent precipitates, thus reducing the MRR of SiC UCAP. Moreover, a larger ultrasonic amplitude generated a greater MRR, but with a smaller deterioration of the machined surface. This investigation reveals that UCAP is a progressive precision machining approach for optical ceramic materials polishing. The proposed polishing process will promote hybrid processing technologies research and simplify the existing SiC machining process to achieve extremely efficient polishing of SiC.