ристик фрикційно-зміцненого шару покриття Ni-Cr-B-Si-С також обумовлене його насиченням елементами середовища та мастила (Карбон, Фосфор). Ключові слова: тверде захисне покриття, мікроструктура, карбіди, бориди, мікротвердість, опір зношуванню, сталь 45. Structural-phase changes and wear of the gas-flame coating of Ni-Cr-B-Si-C system on steel 1045 are investigated experimentally under conditions of its intense deformation by the friction with a shear component of the load in the transmission oil. Using light microscopy, scanning electron microscopy, X-ray spectroscopy and X-ray structural-phase analysis, the morphology, microstructure, phase and chemical compositions of the Ni-Cr-B-Si-C coating are investigated before and after tribological tests. As found, under conditions of the applied normal (250 MPa) and shear (P SH = 30-50 MPa (20%)) stresses in the contact zone the Ni-Cr-B-Si-C coating exhibits a twice higher wear resistance as compared to the base material (steel 1045). The main factors for increasing the wear resistance and reducing the friction work of the coating Ni-Cr-B-Si-C is the presence of the uniformly dispersed particles of Ni and Cr borides, Cr carbides, and Ni silicides in the nanostructured Ni-based solid solution matrix. The increase in tribotechnical characteristics of the friction-strengthened layer of Ni-Cr-B-Si-C coating is also due to its saturation with the elements from medium and oil (carbon, phosphorus).

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The regularities of the wear of the steel 1045 during cutting off the feed of a lubricant under the non-stationary friction conditions were established. The influence of the properties of the secondary structures, formed on the contact surfaces under conditions of rolling with a different degree of slippage, on the wear of advancing and lagging surfaces was determined. The influence of specific friction work, the degree of hardening -weakening of surface layers of metal and the intensity of saturation by active elements of near-surface layers of metal on the wear resistance of friction pairs is examined. The change is established in localization of the depth of spreading the stressed and deformed state of material of the contact surfaces with an increase in the slip rate from 0.315 m/s to 1.14 m/s at rolling with the slippage.

The influence of slip velocity at rolling with slippage on the intensity of heat release in the local contact at different modes of lubricating action was examined. Efficiency of using different procedures for calculating a temperature increase in the friction contact under conditions of dominating elastohydrodynamic and boundary modes of lubricating action was shown. The interrelation between the processes of heat release intensity in tribotechnical contact and wear of friction pairs was established. It was analyzed that the locality of the increased wear in the central section of the contact line is determined by a change in the stress-strained surface condition at friction and by the occurrence of stress concentrator center.