A technology for the deposition of diffusion titanium coatings from liquid metal media on hard alloys of TK (WC+TiC+Co) and VK (WC+Co) systems is described. It is shown that the diffusion saturation of hard alloy tools of these types by titanium from the Pb-Bi-Li melt in a temperature range 1000-1100°С and subsequent heat treatment results in a seven-fold increase of the wear resistance of the tools due to the formation of a diffusion coating. The thickness of the coatings varies depending on the temperature and deposition time and ranges from 2.6 to 6 μm on TK alloys and from 2 to 5.4 μm on VK alloys. The coatings consist of two layers, the surface one and transition one. The results of elemental and metallographic analyses are presented. The microhardness of a coating on hard alloy T15K6 is about 30000 MPa and on the hard alloy WC-8Co is 25000 MPa. The high microhardness of the coatings is caused by their formation on the basis of titanium carbide TiC, while other elements are driven depthward the material to coat. It has been found that the elemental composition of the coatings depends on the composition of the hard alloy under coating. The concentration of titanium in the surface layer of the tool amounts 87.6 % for VK alloys and 93 % for TK alloys. The transition layer is characterized by approximately equal concentrations of titanium and tungsten (about 20 to 25 %) and a reduced microhardness. The diffusion coatings are characterized by a smooth change of the concentration of elements with depth and good adhesion to the base material.

The technology of applying diffusion titanium coatings from the medium of low-melting liquid-metal melts to hard alloys of the TiC-WC-Co and WC-Co types is described. It is shown that in the case of diffusion saturation of the surface layers of a hard alloy tool of the TiC-WC-Co and WC-Co types with titanium from the Pb-Bi-Li-Ti melt, preliminary carburization is an obligatory stage in the process of coating formation, and allows avoiding the formation of a decarburized zone under the diffusion layer. The effect of preliminary carburization on the phase composition of the coated hard alloy is shown. As a result of the phase analysis, it was revealed that the surface layer contains such phases as WC, TiC, Co 2 C, Co-C. In this case, titanium carbide TiC is formed due to the destruction of cobalt carbide upon further diffusion saturation with titanium. In the absence of carburization, the formation of a decarbidized layer was revealed, which differs from the coating and the base in lower microhardness, the drop in microhardness is about 1000 MPa. After carburization, there was a slight increase in the hardness of the coated parts from 89 to 91 HRA. Characteristics such as the microhardness of the carburization zone and its length depend on the temperature and duration of the preliminary carburization, as well as on the elemental composition of the material to be coated. Carburization was carried out in the temperature range from 950°C to 1150°C from 30 to 120 minutes. After saturation with carbon, the thickness of the carburization zone was from 2 to 25 μm, the microhardness from 16700 to 17150 MPa for the WC-Co alloy and from 18750 to 19200 MPa for the TiC-WC-Co alloy. The hardness of the layer under the coating ranged from 27000 to 28500 MPa for the TiC-WC-Co alloy and from 19300 to 23500 MPa for the WC-Co-type alloy.

The analysis of the strengths and weaknesses of the existing technologies aimed at improving the performance properties of carbide-tipped tools is presented. The results of studies into the process of diffusion metallization by titanium of a carbide-tipped tool TK type from the media of fusible liquid-metal solutions is given. The influence of titanium diffusion coatings on the durability of carbide tools is investigated. A method of providing formation on hard alloys for wear-resistant titanium high-quality functional coatings is described. The thickness of the coating varies depending on the temperature and exposure time, and ranges from 4 to 6 μm. The hardness of the coatings obtained depends on the temperature of the coating and modes of pre-carburizing, and varies from 24100 to 30000 MPa. The microstructure of the coatings is investigated. The coating consists of two layers: the coating and the transition zone, the size and hardness of which depends on the conditions of pre-carburization and modes of application of the coating. The dependence of the coatings thickness on the duration of the plates exposure in the melt, the temperature of coating composition from the coated hard alloy is investigated.

Continuous phase diagram 3 - δ - log pO - T of the nonstoichiometric perovskite LaSrCoO was obtained in a gas flow reactor by means of the quasi-equilibrium oxygen release technique. The thermodynamic properties of oxides were determined as a function of oxygen nonstoichiometry. Within the framework of the itinerant electron model, the dependence of the oxide nonstoichiometry on the oxygen activity was related to the density of electronic states near the Fermi level.