DEVELOPING A TECHNOLOGY FOR OBTAINING COMPOSITE MATERIALS BY HOT PRESSING WITH METALLIZED DIAMOND GRAINS

Abstract

A new technology has been developed for the manufacture of diamond tools with a bond of 34% Fe+6% Ni+32% Cu+8% Sn+10% WC+10% Сч18 and with titanium metallized diamond grains of HSD90 (АС200) grade, including the processes of manufacturing a composite mixture, cold pressing, sintering, hot pressing and machining. Optimal sintering and hot pressing regimes were selected and substantiated: sintering temperature: 800 ± 200C, holding time: 0,75...1,0 hour, hot pressing temperature: 850 ± 100C, holding time: 25...30 minutes, specific pressure: 80...100 MPa, in this case the hardness of the composite is 60...102 HRB, impact strength KCU 2...36 kJ/m2, shear strength is 23...160 MPa. It is shown that the composite material has a heterogeneous structure: the matrix is mainly a mixture of α (hard alloy of tin in copper - with a 13,5% tin content) and δ phases (Cu31Sn8), in which solid solutions of α iron and nickel, as well as intermetallic phases with tin and copper, and fillers - grains of graphite and tungsten carbide, are seen as separate grains. At the same time, the presence of gray cast iron in the composite leads to the formation of free graphite, which improves the antifriction properties of the composite.