Basic research on chemical mechanical polishing of single-crystal SiC—Electro–Fenton: Reaction mechanism and modelling of hydroxyl radical generation using condition response modelling

Hydroxyl radicals (·OH) can effectively oxidise and corrode single-crystal SiC, and are used for chemical mechanical polishing (CMP). The generation rate of ·OH and its total concentration produced by a CMP process based on the Electro-Fenton reaction can be effectively controlled by regulating the electric field parameters, thereby improving the polishing effect of SiC. The effects of initial H 2 O 2 concentration, Fe 3 O 4 concentration, and voltage on ·OH were studied, and the reaction mechanism was also revealed. Moreover, a conditional-response mathematical model for ·OH generation was established. The generated ·OH first increased and then decreased with increasing initial H 2 O 2 concentration, Fe 3 O 4 concentration, and voltage. When these parameters were 7.5 wt%, 1.5 wt% and 0.75 V, respectively, a maximum total ·OH concentration of 9545.776 μmol could be obtained. The conditional-response mathematical model established with initial H 2 O 2 concentration, Fe 3 O 4 concentration, and voltage can accurately predict the total generated ·OH concentration with a relative prediction error of less than 10%. Controlling the electric field parameters can accelerate the conversion of Fe 3+ to Fe 2+ , increasing Fe 2+ concentration and enhancing catalytic effect. On the other hand, it also generates a small amount of H 2 O 2 in situ on the cathode, which slows down H 2 O 2 consumption. Furthermore, the Pt anode oxidises water to generate a small amount of ·OH. These combined effects promote ·OH generation. Additionally, the total ·OH concentration achieved in this work was 48.69% greater than that produced by the Fenton reaction. This indicates that applying the Electro-Fenton reaction to CMP of SiC improves the polishing effect. • Reaction mechanism of Electro-Fenton reaction was revealed. • Contribution of voltage to Electro-Fenton reaction was studied. • Total ·OH concentration increased by 48.69% in Electro-Fenton than Fenton reaction. • Conditional-response model for ·OH with error of 10% was established and verificated.