Structural-Phase State of the Interphase Boundary at Thermal Diffusion Metallization of Diamond Grains by Fe, Ni and Co

Abstract

Structural-phase state of the diamond-metallized coating interphase boundary after thermal diffusion metallization of diamond grains by transition metals Fe, Ni and Co were studied. Metallization were conducted under temperature-time mode corresponding to the sintering of cemented carbide matrices with Cu impregnation. The structural-phase state of the metallized coating and diamond-coating interphase boundary was studied by scanning electron microscopy, X-ray phase analysis and Raman spectroscopy. A metallized coating strongly adhered to the diamond forms during thermal diffusion metallization of diamond by iron. The metallized coating has a complex structural phase composition of iron, a solid solution of carbon in iron and graphite phases. Nickel and cobalt cause intense catalytic graphitization of diamond with the formation of numerous traces of erosion on its surface under the heating conditions specified in the experiment. The observed weak adhesive interaction of these metals with diamond is probably due to the high melting temperatures of the Ni-C and Co-C eutectics, which does not allow the metals to react with diamond under given experimental conditions.