Abstract
Scratching experiments have been carried out on ZrO2, Al2O3, Si3 N4 and SiC materials by using the diamond tool which consists of four pyramidal shape diamonds. It is found that in Al203, Si3N4 and SiC radial cracks appear below the grooves scratched by inner two point diamonds, where the material is constrained between other two point diamonds. Only in the case of SiC, as the radial cracks penetrate towards other grooves from the inner two grooves, surface portions are removed. Therefore no microcracks are observed. It is also found that microcrack clusters exist below the grooves of Al2O3 and Si3N4. In ZrO2, cracks occurred only near the surface of specimen, it is observed that no cracks penetrate towards the inside of material like other materials.
