Scratching of SiC ceramics at two dimensional pre-stressing

A stress field model was built to study the effects of pre-stressing value, normal and tangential load on the three principal stresses and maximum shear stress when the silicon carbide (SiC) ceramics were scratched under two dimensional pre-stressing, and the scratching tests of SiC ceramic were conducted by using a Rockwell diamond indenter at different pre-stress values and normal loads. Scratching induced damage was assessed and characterised via destructive inspection techniques and progressive lapping techniques combined with the digital microscope. Acoustic emission (AE) technology was also used for the online monitoring of the damage. The results showed that, for a given scratching load, the amplitude of AE signals was reduced as the pre-stress values increasing, and surface/subsurface damage of SiC ceramics induced by two dimensional pre-stress scratching was less than that by conventional scratching. So one can believe that the two dimensional pre-stress method can contribute to decreasing the machining damage of brittle materials.