Magnetic field-assisted ECDM of SiC_p/Al composites: process optimization and validation

Silicon carbide-reinforced aluminum matrix composites (SiCp/Al) are widely applied in aerospace and electronics for their excellent mechanical performance. However, conventional electrical discharge machining (EDM) of SiCp/Al suffers from severe electrode wear, poor surface integrity, and recast layer formation. To overcome these challenges, this study proposes magnetic field-assisted electrochemical discharge machining (MF-ECDM), replacing the MF-EDM dielectric fluid with a low-conductivity NaNO3 solution. A single-factor experiment investigated how electrolyte conductivity influences machining behavior. Results revealed that increasing conductivity decreases material removal rate (MRR) and relative tool wear ratio (RTWR), but enlarges overcut (OC). Grey relational analysis with orthogonal experiments identified optimal parameters, achieving MRR of 16.75 mm3/min, and OC of 110 µm. Furthermore, a dual sacrificial layer technique was developed to improve small-hole machining by enhancing electrolyte-wall contact, reducing stray corrosion, and compensating for electrode wear. Under optimized conditions, MF-ECDM reduced tool wear by 25–27.71% and improved surface quality compared with EDM and MF-EDM, demonstrating potential for high-quality machining of ceramic-reinforced composites.碳化硅颗粒增强铝基复合材料（Silicon carbide-reinforced aluminum matrix composites, SiCp/Al）凭借优异的力学性能，被广泛应用于航空航天与电子领域。然而，传统电火花加工（electrical discharge machining, EDM）加工SiCp/Al时存在电极损耗严重、表面完整性差以及再铸层生成等问题。为解决上述挑战，本研究提出磁场辅助电化学放电加工（magnetic field-assisted electrochemical discharge machining, MF-ECDM）工艺，以低导电率硝酸钠溶液替代磁场辅助电火花加工（magnetic field-assisted electrical discharge machining, MF-EDM）所用的绝缘工作介质。通过单因素实验探究了电解液电导率对加工性能的影响规律。结果表明，随着电导率升高，材料去除率（material removal rate, MRR）与相对工具损耗率（relative tool wear ratio, RTWR）均出现下降，但过切量（overcut, OC）有所增大。结合正交试验的灰色关联分析确定了最优工艺参数，实现了16.75 mm³/min的材料去除率与110 µm的过切量。此外，本研究还开发了双重牺牲层技术，通过强化电解液与壁面的接触、减少杂散腐蚀以及补偿电极损耗，实现了小孔加工性能的提升。在优化工艺条件下，相较于电火花加工与磁场辅助电火花加工（MF-EDM），MF-ECDM可将电极损耗降低25%~27.71%，并改善了加工表面质量，证明该工艺在陶瓷增强复合材料高质量加工中具有应用潜力。