Structure of diamond-matrix interface and durability of diamond tool obtained by diamond metallization with chromium during WC–Сo briquette sintering with copper impregnation

Abstract

The paper studies the structure, elemental and phase composition of the diamond-matrix interface in a diamond tool for abrasive wheel dressing manufactured using a new hybrid technology that combines thermal diffusion metallization of diamond with chromium and sintering of a matrix based on WC–6%Co carbide powder mixture with copper impregnation in a single cycle of vacuum furnace operation. During matrix sintering, the compact arrangement of chromium powder particles around diamond grains and the shielding effect of copper foil create favorable conditions that ensure the thermal diffusion metallization of diamond. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy show that temperature-time modes and sintering conditions specified in the experiment provide for a metal coating chemically bonded to diamond that is formed on the diamond surface and consists of chromium carbide phases and cobalt solid solution in chromium providing durable diamond retention in the copper-impregnated carbide matrix. In this case, matrix structure and microhardness except for areas directly adjacent to the diamond-matrix interface remain the same as for the matrix of a powder mixture sintered without chromium. Comparative tests of similar diamond dressing pens were carried out and showed the high effectiveness of the hybrid technology in obtaining diamond-containing composites intended for tool applications. It is shown that the specific productivity of a pen prototype made using the hybrid technology was 51,50 cm3/mg when dressing a grinding wheel of green silicon carbide that is 44,66 % higher than the similar indicator for the sametype check pen made by the traditional method.