Factors Affecting Diamond Retention in Powder Metallurgy Diamond Tools

This paper describes the effects of principle factors which have an influence on potential diamond retention capabilities in powder metallurgy diamond tools. Investigations were carried out using a 3-D computer model of diamond particle embedded in a metallic matrix. The proposed model assumed that the material was fully densified by the hot pressing technique and then cooled down to room temperature. The energies of plastic and elastic deformation of the matrix around the diamond grit as well as recoverable strain energy accumulated in the grit on cooling were calculated. The effects of Young's modulus and yield strength of the matrix as well as friction between diamond and matrix on these energies were analysed. The obtained results have shown that a matrix characterised by high yield strength ensures better diamond retention capacity whereas high Young's modulus of the matrix and its chemical affinity to carbon, which increases friction at the diamond-matrix interface seem to have lower importance.