The normal loads (perpendicular to the scratching direction) were very small compared with the axial (perpendicular to the workpiece surface) and tangential (parallel to the workpiece surface) loads in UVAS tests. Therefore, we only analyzed the axial and tangential loads in this paper. Fig. 4 shows the loads in UVAS and traditional scratch tests at the same speed. Because data were not reliable at the beginning and end of the scratching process, only the middle part of each scratch was selected for analysis. The loads in both UVAS and traditional scratch tests fluctuated, which was mainly a result of the diamond indenter scratching the SiC.
Compared with those during the traditional scratch tests, loads were decreased in UVAS tests. The average axial load decreased by 28.4% and the average tangential load was reduced by 46.9%. The axial loads were greater than the tangential ones in both the UVAS and traditional tests.