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Peculiarities of the formation of secondary structures on the surface of a diamond-like coating are studied on the example of a friction contact between a steel ball and a diamond-like coating. The friction surface was examined in various areas; the zone of wear products (the boundary of the friction track) and the original surface outside the friction area. It is shown that secondary structures with a high content of iron, nickel, manganese, chromium, and oxygen are characteristic of areas with the highest wear resistance. Such secondary structures are formed because of the intense interaction of the diamond-like coating with the steel of the ball during dry friction.

Antifrictional properties and surface parameters of Al-Si-Cu-Sn-Pb alloys have been investigated. The effect of iron addition (∼1%) on the structure and tribological properties of aluminum alloy samples has been studied. Tribological properties were explored using the "shoe-roller" scheme with step-by-step pressure changes. The investigations were carried out both in and without a lubricant. The SEM-(with elemental analysis) and SPM-microscopy methods were applied to study sample surface and under-surface layers of the samples at the transversal sections. After tribological tests have been carried out, the topography of both surface and under-surface layers at the transversal sections has been studied. During the tests without lubrication solid particles, presumably, oxides were formed. The particles increase the surface destruction, thus, doing their part of an abrasive and contributing to (scuffing) score. After testing in the lubricant particles containing silicon and copper and having a rounded shape were also formed. These particles remain on the surface and are rolled in the lubricant. They creating a kind of a "protective cover" contributing to the contact pair stable operation. The under-surface layer 50-100 µm thick formation was found at the sections after tribological tests without lubrication. The samples sections were prepared after testing with lubrication. The study of the samples sections demonstrated the formation of the under-surface layer with thickness 30-40 µm. The elements redistribution in these layers was shown. After the tribological tests were carried out, the counterbodies (rollers) were also explored. The SPM method has been shown the film formed on the surface is uneven in thickness after tests without lubrication. This leads to the macrorelief development during friction and can lead to (scuffing) score. On the contrary, after tests in lubricant the secondary structures film formed is distributed on the surface as a thin uniform layer. This film has the protective properties. It was shown that alloys containing iron (up to 1%) have good tribological characteristics when tested both in and without the lubricant. Thus, they can be used as antifrictional materials.

Experimental aluminum alloys with the addition of iron, which model the materials obtained with the addition of recyclables, were investigated. The use of the recyclable (silumin waste, production waste, remelting of canned scrap, etc.) seems to be promising for the national economy. In the work, the alloy of the Al-6 % Sn-5 % Si-4 % Cu (mass. %) system was used as a base, to which iron (1 %) and other elements (bismuth, lead, manganese) were added. The samples under investigation were subjected to heating up to 500°C and cooling in various regimes. It was shown that the best results were achieved with cooling in water: the phases were spheroidized and properties were improved. Complex method of microscopy, including optical, electronic (with X-ray spectral microanalysis), and probe microscopy was used, in order to study alloys before and after tribological tests. An investigation of the initial structure of the samples showed that the combined addition of iron with manganese (0.5 %) led to the formation of favorable skeletal phases. The tribological tests without lubrication which modeled the extreme conditions of operation were carried out. These experiments showed that the investigated alloy had an increased wear resistance, which could be associated with the formation of skeletal phases. After tribological tests, significant changes in the structure and phase components at the surface and in the near-surface layer were observed. For the study of this layer, an oblique cut was made, on which near-surface area with a thickness of 50-100 μm was detected.

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