Experimental study on the removal behavior of SiC_f/SiC by traditional and ultrasonic vibration assist scratching with single grain diamond

Due to their excellent mechanical properties at elevated temperatures, Ceramic Matrix Composites (CMCs) are increasingly used in the manufacture of critical components for industries such as aerospace, nuclear and automotive. However, its high hardness, brittleness, anisotropy, and non-homogeneity lead to severe tool wear and uneven cutting process during material removal machining, making it difficult to control the surface quality. To gain an in-depth understanding of the material removal mechanism of CMCs for grinding processing, variable depth-of-cut scratch tests along different scratch directions under conventional and ultrasonic assist conditions were conducted. The results showed that ultrasonic assist scratch (UAS) caused more severe groove exit damage when scratching along the longitudinal direction of the fibers. The high-frequency hammering effect of ultrasonic vibration reduced the bending fracture of the fibers and increased the material removal when scratching along the transverse direction of the fibers, and reduced the area of groove edge chipping. In terms of scratching force, the scratching force along the longitudinal direction of the fibers is less than that along the transverse direction. In addition, ultrasonic vibration makes the material change from the original brittle fracture removal caused by extrusion, shear, and tension to the brittle fracture crack intersection removal prompted by hammering-scratching action, reducing the scratching force.