An experimental study on arcing in arc-enhanced plasma machining technology for etching of silicon carbide ceramics.

Atmosphere plasma etching methods have been applied to the machining of optics. However, due to the high chemical stability and inertness of silicon carbide (SiC) ceramics, it seems difficult to improve the material removal rate (MRR) for conventional etching methods. We have found MRR will be significantly improved while arc forms between the inductively coupled plasma and SiC ceramic surface. This etching method is called arc-enhanced plasma machining (AEPM) technology. Arc-enhanced plasma (AEP) is represented as the secondary of a high-frequency transformer considering capacitive coupling in this paper. Radio frequency (RF) voltage in AEP is measured. The RF voltage of plasma is extremely high to form arc when plasma is close to the SiC ceramic surface. The measurement results of RF voltage at the metal-plasma interface show that the arc formation is related to the distance between source jet and workpiece ( D ). When D is small, a nonconductive layer of cooled argon forms over the workpiece surface, preventing arcing. Trenches are etched on SiC ceramic surface with different D , finding that the MRR is improved under the arcing action and the optimal D is obtained. [ABSTRACT FROM AUTHOR]