Study on ultrasonic-assisted scratching and mirror grinding of silicon carbide based on truncated coarse diamond wheel

Abstract

Ultrasonic vibration-assisted grinding (UVAG) has been proven to be an effective method for processing hard and brittle materials such as silicon carbide (SiC). However, most UVAG processes use fine-grained diamond grinding wheels to achieve higher accuracy, which brings about the problems of heavy wear and frequent dressing, and lower material removal rates. Therefore, a new UVAG method based on coarse-grained diamond grinding wheel was proposed to realize mirror grinding of SiC. In this paper, the effects of ultrasonic power on the critical depth and grinding force were investigated during the brittle-ductile transition of SiC material removal. The effects of grinding process parameters and ultrasonic power on the ground surface quality were also analyzed and compared. The results show that the ductile removal region and the critical depth of brittle-ductile transition increase while the critical scratching force decreases when the ultrasonic power increase in a certain range. When the ultrasonic power is 40 % (ultrasonic amplitude of 2.36 μm), the longest ductile domain length, the largest critical brittle-ductile transition depth and the least critical scratching force of the scratched SiC surface reached 257.49 μm, 0.608 μm and 4.47 N, respectively. This indicates a significant positive impact of ultrasonic vibration on grinding of SiC. Compared with traditional mechanical grinding, coarse diamond grinding wheels assisted by ultrasonic vibration can achieve better surface quality, reducing the surface roughness of SiC by approximately 65.38 %. The surface roughness reaches the minimum value of 36 nm at the wheel speed of 12000 r/min, feed rate of 20 mm/min, grinding depth of 2 μm, and ultrasonic power of 40 %, resulting in a mirror-like macroscopic surface.