Study of atomized discharge ablation-chemical composite machining of SiCp/Al

Abstract

Electrical discharge-induced ablation machining utilizes the significant chemical energy released by the combustion of oxygen with metals to remove materials, thereby greatly enhancing the material removal rate (MRR). However, in the case of discharge ablation machining of silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al), the effect of oxygen can easily result in the formation of poorly conductive oxides, which in turn affect the machining stability and adversely impact the MRR and quality of the machining surface. To address this problem, this study proposes the use of sodium carbonate (Na₂CO₃) solution as the atomization medium to chemically dissolve the oxide during processing to achieve the effect of atomized discharge ablation-chemical composite processing. The study found that the Na₂CO₃ solution facilitated high-temperature chemical etching behavior in the SiCp/Al atomized discharge ablation process. The Na₂CO₃ solution reacted chemically with and etched away the recalcitrant oxide that formed in the SiCp/Al process area during machining, thereby ensuring efficient and continuous electrical discharge ablation machining. We applied the atomized discharge ablation-chemical composite machining method to mill SiCp/Al. The experimental results showed that the MRR was 2.66 times higher than that of electrical discharge machining (EDM) and 1.98 times higher than that of conventional atomized discharge ablation milling. Moreover, the relative electrode wear ratio was reduced by 76.01% compared with that of EDM and 82.30% compared with that of conventional atomized discharge ablation machining.