High-efficiency electrical discharge drilling of SiC wafers enabled by intensified vapor dynamics in the discharge gap

Electrical discharge machining (EDM) is promising for processing silicon carbide (SiC) power semiconductors due to its independence from material hardness and brittleness. However, its low machining efficiency remains a major limitation for its practical application. This study proposes a low-boiling-point zinc electrode to enhance the vapor effects in the discharge gap and improve the EDM efficiency of SiC, while the underlying material removal mechanism is elucidated through molecular dynamics simulations of the single-pulse EDM process. The zinc electrode significantly improves machining efficiency, achieving an approximately 178% higher machining speed than the copper electrode while maintaining lower surface roughness and fewer edge defects around the machined holes. Under single-pulse EDM conditions, the zinc electrode results in larger discharge crater size and higher material removal per pulse than other electrodes, accompanied by more pronounced zinc deposition on the crater. The combined simulation and experimental results suggest that the enhanced machining efficiency of SiC achieved with the zinc electrode is associated with two factors: First, the zinc electrode generates a high-velocity and high-density vapor jet, which transfers greater momentum to the molten and solid materials within the discharge crater; Second, the deposition of zinc vapor is proposed to account for the weakened interaction between the crater materials and the SiC crater surface, thereby facilitating their removal. The joint effects of these mechanisms promote high-velocity removal of crater materials (molten Si_xC_y, solid Si_xC_y and solid C), thereby increasing the fraction of removed materials within the crater and resulting in a larger discharge crater per pulse. This work systematically elucidates the mechanisms and machining advantages of the zinc electrode in EDM of SiC, providing a basis for achieving efficient SiC machining.