The application of diffusion nicke-copper coatings on hard alloys leads to an increase in the durability of carbide-tipped cutting tools when machining even hard carbide-containing steels at the high cutting speeds, which improves the productivity of the machining process. The analysis of the influence of deposition of nicke-copper coating by the diffusion metallization from environment of the fusible liquid metal solutions at the resistance of alloy carbide inserts of type WC-Co and TiC-WC-Co, and to the quality of the processing of hard alloy high viscosity has been performed.

The technology of diffusion saturation of austenitic steels by chromium and nickel in the medium of low-melting liquid metal melts is shown. The saturation temperature was up to 1050°C, and the duration was up to 8 hours. It was found that it is the most effective to apply coatings according to the technological scheme: pre-carburization-diffusion metallization – final carburization. It was found that the coating consists of 4 layers. The surface layer has a thickness of up to 5 mkm and a microtuberance of up to 19500 MPa. The second layer, up to 12 mkm thick, has a microhardness of up to 7500 MPa. The third, up to 50 mkm thick, has a microhardness of 2300 MPa. In the fourth layer, up to 150 mkm thick, the microhardness gradually decreases from 2300 MPa to the microhardness of the base. At the same time, the total thickness of the coatings is up to 200 mkm.

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Diffusion alloying effect of WC-8%Co and 15%TiC-WC-6%Co hard alloys by Ni-Cu over TiC deposited by diffusion alloying in a low-melting liquid metal medium melt has presented. Such operation abilities of cutting tool as toll life, wear resistance, quality of processed surface can be increase by diffusion alloying in liquid metal melts. Tool life increased by 2.5 times compared to uncoated tools. It was found that kinetic of coating formation depends of the temperature and alloying time. The thickness of the diffusion layer varied up 8 to 27 microns on WC-8%Co; up 9 to 29 microns for 15%TiC-WC-6%Co alloys. The maximum microhardness on 15%TiC-WC-6%Co alloys was 21500 MPa, for WC-8%Co alloys 18000 MPa. It was found that element-phase composition of hard alloy influence to kinetic of diffusion functional coating formation process. Functional diffusion layer on 15%TiC-WC-6%Co alloys have a higher hardness and thickness compared to WC-8%Co.

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