Abstract
Scratching experiments have been carried out on HP-Al2O3 material by using single-point diamonds of conical shape (conical angle 85°, 108°, 128°, 65° and nose radius 1.6μm, 1.1μm, 1.9μm, 45.0μm respectively). With an increase of scratching depth, the material exhibited the following behaviour: macroscopic plastic deformation→scale-like cracking→cracking or chipping. No cracking or chipping grooves were observed only if the groove depth was less than certain values which varied with the diamonds. The crack penetrating depth was approximately in proportion to groove depth. In the case of depth of cut less than 2μm, penetrating depth of crack induced by the diamond of nose radius 45.0μm is almost 8times of those by another diamonds. In depth of cut larger than 2μm, the former is twice as the latter. The coefficients of pile-up increased as depth of cut decreased.
