Study of ablation behavior on 2.5-dimensional C/SiC composites processed via short electric arc milling with various parameters

Abstract

The machinability of 2.5D C/SiC composites is severely limited by their inherent brittleness, inhomogeneity, and anisotropy. Conventional machining techniques are often associated with several drawbacks, including elevated costs, significant tool deterioration, and suboptimal efficiency. In contrast, short electric arc milling (SEAM) emerges as a promising innovation in the field of specialized machining, serving as a crucial technical approach for the effective processing of conductive materials that pose machining challenges. This work explores the surface quality law after short arc machining of 2.5D C/SiC composites under different process parameters and investigates etching damage incurred. To assess the influence of different parameters on the surface quality post-machining, two evaluation indices were established: surface roughness (Sa) and the thickness of the heat-affected layer (HAL). A one-factor test was set up to analyze the voltage and current waveforms, the electron microscopy images of the processed surface, Raman spectra, and the surface energy spectrum, using Sa, HAL, and the microscopic morphology as the detection indices. Moreover, the study demonstrates that the arc discharge energy and the discharge frequency exert considerable influences on the quality of the machined surface. Both the Sa and HAL values increase with higher voltage and duty cycle, while they decrease with rising frequency and electrode rotation speed. Consequently, the surface quality can be enhanced by lowering the voltage and duty cycle and by increasing the frequency and electrode rotation speed. Notably, short arc machining leads to a high-temperature oxidation reaction, primarily producing SiO₂, which serves to prevent further oxidation of the material. However, the process also results in microscopic defects, such as fiber breakage and fiber pull-out. These findings offer both theoretical and experimental foundations for the future realization of high-efficiency and high-quality processing of 2.5D C/SiC composites via SEAM.