The method of system triboanalysis is considered in order to select optimally antifrictional polymer materials (PMs) for metal-polymer plain bearings. It includes the model tribotesting of the PMs and calculation of generalized characteristics of their wear resistance depending on specific friction forces. The method is used to assess the wear resistance of a large number of existing PMs based on polyamide, polytetrafluoroethylene, polyacetal, polyethylene terephthalate and polyetheretherketone. Experimental studies of the specified PM groups were performed on a tribometer operating according to the “pin-on-disc” scheme. The obtained wear resistance characteristics are the basic parameters of a well-known mathematical model describing the kinetics of material wear during sliding friction and an analytical method for calculating metal-polymer plain bearings. The research results are presented in the form of diagrams covering a wide range of specific friction forces, which allows for a visual comparison of antifrictional PMs by wear resistance. The friction patterns of PM in a pair with steel 45 were established, the qualitative and quantitative influence of the type of fillers on the wear resistance of the polymeric materials was analyzed. In each group of PMs under consideration, a composite with maximum wear resistance is noted in comparison with the base (unfilled) polymer.

For a layered material “high-strength coating — base” with different values of the thickness of the strengthened layer, finite element modeling of the stress-strain state formed during friction was carried out. It is shown that with a decrease in the thickness of the coating, a significant increase in the level of shear stresses acting in the base during friction is recorded. The patterns of wear under dry friction conditions of high-chromium steels AISI 304 and AISI 420 modified with nitrogen ions, differing in the hardness of the base and the thickness of the nitrided layer, have been studied. It is concluded that the abnormally high wear rate of a thin nitrided layer in steel AISI 304 is associated with the accumulation of shear strains in the plastic austenitic base during friction, as well as with a high gradient of hardness values along the depth of the hardened layer in the steel and a phase → transformation in the base during frictional interaction. The influence of base hardness on the wear resistance of nitrided steel AISI 420 was studied. It has been estab-lished that an increase in the hardness of the AISI 420 steel base leads to a decrease in the wear rate of thin nitrided layers at the later stages of tribological tests, which is associated with a slowdown in the accumulation of shear strains in the solid steel base during friction.

The paper considers the results of studies on the wear resistance of machine parts made of structural steels during the formation of micropores in their surface layer by the dealloying method based on electrolytic plasma treatment. The technological conditions for the formation of a microporous surface layer by electro-lytic plasma treatment with subsequent modification by ion implantation and ion nitriding are presented. It is shown that the creation of a microporous layer contributes to an increase in the tribotechnical characteristics of surfaces under lubrication conditions. It is shown that the use of the electrolyte-plasma surface treatment method allows high-performance formation of a microporous surface layer that does not require further me-chanical processing, and in one technological cycle is able to polish it. It is shown that the use of preliminary preparation of the surface layer for nitriding using high-energy processing methods can significantly increase the wear resistance of the microporous layer. The results of comparative tests of microporous surfaces with various processing options are presented. It is shown that the use of microporous surfaces in conditions of friction with lubrication makes it possible to increase the wear resistance of 40X and 40KHN steels by about 1.5—2 times, and their nitriding provides an increase in wear resistance compared with simple traditional nitriding by about three times, and compared with microporous surfaces without nitriding by more than 9 times.

The mechanism of the lubricating effect of two model lubricants based on medical vaseline with 0.5 wt. % additives of carbon nanostructures (CNS), namely graphene oxide (GO) and shungite nanocarbon (Sh), under hard friction conditions (friction machine 2070 SMT-1, “disc–roller” friction pair made of hardened steel ShKh15, load 2000 N) has been established. The friction surfaces were examined by confocal laser micros-copy and scanning electron microscopy. The elemental composition of the friction surfaces was determined with the help of energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The contribution of the chemical component (formation of iron oxides) to the anti-wear process was analyzed. It was found that despite the difference in the spatial structure of the used CNSs, the processes occurring in the friction zone are chemically similar. It has been demonstrated that with the use of both model lubricants, protective oxide films consisting of iron oxides (FeO, Fe2O3, Fe3O4) are formed in the contact zone. The chemical composition of the oxide film and the quantitative ratio of the formed iron oxides are not signifi-cantly affected by the type of CNS additives used. The obtained results, together with the studies we per-formed earlier, demonstrate that the mechanical component, associated with the spatial organization of CNS additive, makes the decisive contribution to the anti-wear process under hard friction conditions.

The probability of formation of new phases on tribo-conjugated metal surfaces of the contact zone at physicochemical interactions of lubricating and cooling technological products (LCTP) or their components with juvenile metal surfaces of iron and titanium when cutting tools are used has been substantiated. Studies of changes in the appearance of surfaces of steel 45 and titanium alloy BT1-0, formed during cutting with the use of air and its separate components (oxygen and nitrogen), including those activated by corona discharge, as LCTP, at the pressure of external media 10–1 mm Hg have been carried out. The best surface quality of steel 45 was recorded at activation of SDS by negative potential on the corona electrode. For titanium alloy VT1-0 the best surface quality was recorded at activation of LCTP by positive potential on the corona elec-trode. It has been established that titanium, having a higher chemical affinity to oxygen, has a higher chemical affinity to free-radical fragments of oxygen-containing organic LCTP. It has been suggested that the CRMs containing organic compounds can be used in the treatment of both iron and titanium, as well as their alloys.

Improving the efficiency of the grinding treatment process of machine parts and mechanisms provides for the choice of rational processing modes, characteristics of the abrasive tool and coolant, as well as the selection of modifying additives impregnated into the body of the circle. The work investigated the connec-tions between the chemical composition, the main physicochemical and working operational and technolog-ical properties of the lubricating cooling process fluid, which determine the effectiveness of its action in order to increase the processing efficiency and surface quality during grinding. The studies were carried out to identify the nature of physicochemical phenomena in contact between abrasive grain and metal using the “RSZ-2” device. The mechanism of influence of thermoelectric phenomena on the processes of interaction of bodies in the presence of lubricating cooling process fluid, during grinding has been established. The mechanism of the influence of thermoelectric phenomena on the processes of interaction of bodies in the presence of lubricating cooling process fluidduring grinding is revealed. It is shown that the grinding process can be considered as a continuous change in the energy of atomic and molecular interactions in a three-phase system of metal-lubricant-abrasive grain boundaries.

The research includes the development and analysis of a mathematical model of a truly viscous lubricant in a modified sliding bearing design with a composite fluoroplastic coating on the surface of the shaft and a groove, which helps to improve the distribution of lubricant and increase the durability of the system. Based on the equation of motion, the liquid lubricant under study, the continuity equation and the equation of state, new mathematical models have been obtained that additionally take into account such a parameter as com-pressibility. The novelty of the work lies in the development of a methodology for engineering calculations of the design of a radial sliding bearing with a polymer coating, taking into account the presence of a groove, as well as the dependence of viscosity on pressure and compressibility of the lubricant, allowing to determine the value of the main tribotechnical parameters. The results of the study provided a reduction in errors in bearing capacity by 11—13 %, and in coefficient of friction by 9—12 % of the modified bearing in compar-ison with traditional designs. As a result, it was possible to achieve an increase in the service life of radial bearings, which is of great importance for their industrial application.

By means of additive electron beam growing BrAMts9-2/12Kh18N9T alloys with the following con-centration ratios of 90:10, 75:25, 50:50 and 25:75 were obtained. In the work the microstructure, mechan-ical and tribological properties of the obtained materials were investigated. Balls of Si3N4 were used as counterbodies, which slid without lubrication on disks of the obtained materials. The maximum and mini-mum levels of tensile strength were 813 MPa and 635 MPa, achieved for samples containing BrAMts9-2/12Kh18N9T in the ratio of 50:50 and 75:25, respectively. It is shown that with an increase in the steel content from 10 to 75 %, there is an increase in the average friction coefficient and wear intensity. There is a change in the wear mechanism from wear due to excessive plastic deformation to abrasive wear. This transition is accompanied by a decrease in the fluctuations of the friction coefficient values. Despite the presence of subsurface defects in alloys with a large amount of steel, their average friction coefficient values are in the range of smaller values (0.38—0.42) compared to materials known from the literature, the friction coefficient of which is in the range of 0.46—0.52 under comparable tribological test conditions. Thus, the materials obtained in the work have high properties that allow these materials to be used in the manufacture of highly loaded parts and units of shipping equipment subject to wear under aggressive en-vironments.

The article presents the results of experimental studies of the durability of protective oxide coatings of 12X18N10T stainless steel in a lead coolant environment, when simulating an emergency situation of “inter-circuit leakage of a steam generator”. The tests were carried out on the FTM-2023 NSTU stand in a lead coolant with a temperature of up to 430—450 °C, without circulation. The tube bundle for simulating a steam generator leak during the outflow of the light phase is two rows of 22x3.5 pipes welded to a plate with a pitch of 33 mm. The data were obtained for tube bundles with two different types of holes for the outflow of the vapor phase: a slit hole of 13x1 mm and a round hole with a diameter of 4 mm. The processing and analysis of the results allowed us to conclude that when a steam-water mixture enters the HLMC circuit, the oxide coatings become thinner depending on the location of the tube in the bundle and the shape of the discharge hole. There is a noticeable decrease in microhardness (by 49 HV for a tube bundle with a round discharge hole and by 23 HV for a tube bundle with a rectangular discharge hole), which is more pronounced when approaching the discharge hole and depends on the orientation of the tube surface onto which the mixture enters, relative to the leak. The obtained data are recommended for use in assessing the consequences of a large leak in a horizontal steam generator in installations with heavy liquid metal coolant.

The mechanisms of contact interaction of diamond-containing composite materials (diamond cutting disk segments) during cutting of steel and concrete have been studied by electron scanning microscopy. It has been established that the increase in the cutting ability of the diamond cutting disc when the concentration of diamond grains in the diamond-containing composite material of the segments increases is associated not only with an increase in the number of diamond grains on the segment surface, but also with a change in the mechanism of contact interaction between the diamond-containing composition and the material being cut. It was found that the increase in the size of grains, even with a small change in the concentration (from 17.5 to 25 relative %) in the segment changes the cutting ability of the tool. Diamond grains reduce the contribution of frictional interaction between the bond and the processed material, and their higher concentration in the segment leads to a decrease in impact loads on the grain. When cutting a steel tube, an increase in the con-centration of diamond grains reduces the frictional component of the contact interaction of diamond-contain-ing composite material with steel, reducing the thermal effect of frictional interaction, and the increase in their size contributes to the increase in the strength of their fixation by the bond, leveling the influence of the thermal effect of frictional interaction of the bond with steel and the increase in its temperature in the zone of frictional contact.

This work is devoted to the analysis of the wear-free effect for carbon steels subjected to surface alloying with metallic bismuth using the technology of short-pulse laser melting. Tribological studies were performed in conjunction with industrial metal alloys — gray cast iron, nickel-aluminum bronze, aluminum alloy. Under boundary lubrication conditions, the bismuth-alloyed steel surface tested in contact with the analyzed alloys showed ultralow value of the friction coefficient in the range from 0.04 to 0.08. It was established that the high fatigue strength of the aluminum alloy and the absence of adhesion with the bismuth-alloyed steel sur-face provide conditions that implement the wear-free effect (zero wear) at friction speeds of up to 9 m/s and normal loads of up to 250 N. Metallographic analysis and 3D profilometry of friction surfaces revealed that the process of self-organization of the contact zone is athermal in nature (without frictional heating) and is determined by the plastic flow of the contacting surfaces without their mutual destruction.