Control principle of anodic discharge for enhanced performance in jet-electrochemical discharge machining of semiconductor 4H-SiC

Abstract

Implementing anode discharge into electrochemical jet machining (EJM) makes it possible to process semiconductor material 4H-SiC. However, the characteristics and control principle of anodic discharge behavior in EJM remains unclear, while it significantly influences material removal and EJM precision. The present study reveals discharge behavior and its impact on material removal by controlling the imposed electrical and chemical conditions. The physicochemical properties and spatiotemporal distribution of discharges are discussed by analyzing the plasma region's temperature, luminescence, and material removal fashion. The findings reveal that discharges are preferentially ignited in certain areas where the current density is concentrated. The discharge intensity and location are controllable by the pulse cycle and electrical field distribution inside the jet (i.e., changing the jet angle). Reducing pulse duration leads to more localized and mild discharges, improving machining precision. A gas ionization-dominated anodic discharge model is proposed. Both discharge and electrolyte types exert significant influence on material removal. Using a DC supply provides a maximum machining rate of 1.44 mm/min. Meanwhile, an optimal surface finish Ra 170 nm and high shape precision with no overcut is achievable by applying high-frequency AC of 1000 Hz.