IMPREGNATION OF MICRO- AND ULTRADISPERSED DIAMOND POWDERS WITH COPPER-BASED ALLOYS IN THE MANUFACTURE OF ABRASIVE TOOL

Abstract

The paper is devoted to studying high-temperature vacuum impregnation of micro- and ultradispersed diamond powders (MPA and UDPA) of the ASM 50/40, ASM 14/10, ASM 10/7, ASM 5/3, ASM 1/0 grades, as well as metal powders Ti, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, and their mixtures with some copper-based alloys. It has been determined that ASM 50/40 and ASM 14/10 diamond powders can be impregnated with an adhesive-active copper-based alloy Cu–20.3 Ti–4.6 Sn–2.8 Ni–0.15Si–0.1 B. However, diamond powders of grades АСМ 10/7, АСМ5/3 and АСМ 1/0 were in no way impregnated with such an alloy, as well as non-adhesive active alloys Cu–15.0 Sn, Cu–15.0 Ge, Cu–18.8 Ga. Impregnation of metal powders Ti, V, Nb, Cr, Fe, Co, Ni was successful, unlike Ta, Mo, and W, which were not impregnated with alloys Cu–15.0 Sn, Cu–15.0 Ge, Cu–18.8 Ga (except for the adhesive-active alloy). A thin layer of oxides remained on the surface of metallic powder particles. Metal powders of the first group (Ті, V, Nb, Cr, Fe, Co, Ni) were unstable and easily reduced by vacuum heating, being, therefore, wetted and impregnated with the studied alloys. In the second group (Ta, Mo, W), chemically resistant surface oxides interfered with wetting-impregnating processes. The process of contact-reaction impregnation of MPA or UDPA mixtures with metal powders Ta, Mo, W facilitated the obtaining of a non-porous high-strength composite material in which the diamond grains were securely fastened. The oxides from these metals were partially reduced by diamond carbon. The grain surfaces of diamond powders were metallized (covered with a thin layer of metal) due to partial evaporation of oxides and their deposition on the surface of diamond grains and reduction to pure juvenile metals. Thus, the two components of the mixture were very well wetted and impregnated with the investigated melts. The use of an adhesive-activated alloy or a mixture of powders MPA and UDPA with Ti, V, Nb, Cr, Fe, Co, Ni is not desirable due to the chemical interaction of Ti, V, Nb, Cr with the material for tool production or diamond graphitization in the presence of process catalysts Fe, Co, Ni.