A NEW VIEW ON THE MECHANISM OF DIAMOND POLISHING

In this paper, a concept is proposed for the development of a model wh ich describes the well-known anisotropic behaviour of diamond observed friction and polishing. In the view of recently obtained results, as well as data found in the literature on the nature of the friction and polishing debris and the scratched and polished surface, a mechanism involving a local transformation from sp(3) to sp(2) hybridised carbon is considered. It is assumed that under high compressive stresses app lied parallel to the surface, work done by bending the bonds locally e xceeds the energy barrier for rehybridisation. If the direction depend ent Poisson ratio indicates correctly the response of the diamond stru cture upon high compressive stresses in terms of bond bending angles, the proposed concept of mechanically induced degradation of diamond le ads to a simple explanation of the anisotropy in friction coefficient and the removal of material during polishing in the soft direction.