Effect of dissolution behavior on electrochemical jet machining of SiCp/Al metal matrix composite

Silicon carbide particle-reinforced aluminum matrix composites (SiC_p/Al) are advanced materials with challenging machinability for traditional techniques. Electrochemical jet machining (EJM), an emerging variant of electrochemical machining, offers a promising alternative for machining SiC_p/Al. Previous studies on EJM of SiC_p/Al have observed anomalous W-shaped removal profiles contradicting classical EJM theory. However, the underlying mechanisms remain unclear. This study investigates this unique phenomenon through an innovative method integrating electrochemical analysis and multiphysics simulation. Electrochemical analysis reveals special current efficiency characteristics of SiC_p/Al dissolution, which are sensitive to not only current density but also flow velocity. Additionally, a product-transport-related mechanism is proposed to elucidate the dependence of current efficiency on electric and hydraulic conditions. Increasing current density or decreasing flow velocity promotes the accumulation of electrolytic products between undissolved SiC particles, impeding matrix dissolution and reducing current efficiency. Furthermore, a multiphysics model considering the electro- and hydro-dynamics governed dissolution behavior is developed to simulate EJM of SiC_p/Al. Results indicate substantially low current efficiencies in the machined central region are induced by the synergistic effects of high current density and low flow velocity herein, thereby slowing the dissolution despite high current densities. Consequently, a central protrusion forms in the machined region, producing the observed W-shaped removal patterns. These findings provide in-depth insights into the EJM mechanism for metal matrix composites, aiding in material removal mechanism-driven machining process development.