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).