The influence of silica addition (in the range of SiO₂ concentrations from 0 to 6 mol. %) in aluminatoughened zirconia (stabilized in tetragonal phase by calcium oxide) on its friction coefficient and wear rate has been studied. It is found that with elevation of SiO₂ concentration, both characteristics experience nonmonotonic changes with an overall increasing trend. The dependences comparative analysis of mechanical properties (microhardness, fracture toughness and brittleness index), tetragonal phase t-ZrO₂ transformability and wear rate on SiO₂ concentration in the investigated composite ceramics has been carried out. It is shown that the non-monotonic character of wear rate dependence on SiO₂ concentration is due to the competitive influence of changes in microhardness, fracture toughness and t-ZrO₂ transformability caused by the silica addition into ceramics. A proposal has been made on the feasibility of manufacturing silicon-containing ceramics (possessing increased values of fracture toughness and compressive strength, as well as plasticity reserve at room temperatures) with a near-surface SiO₂-free layer retaining the preferred values of microhardness, friction coefficient and wear rate.

We developed a methodology and setup for testing materials for resistance to gas-abrasive wear at normal and elevated temperatures up to 1000 °C. The test results allow us to choose welding materials for restoring the working surfaces of components in drawbench machines, industrial fans, charging devices for blast furnaces, gas turbine installations, and other equipment. We determined the wear rate of certain welded alloys based on the test temperature, gas-abrasive flow velocity, and the attack angle of the specimen surface. We elucidated that under conditions of high-temperature gas-abrasive wear at small attack angles and increased velocity of abrasive particles, it is advisable to use eutectic alloys with reduced content of expensive carbideforming elements and carbon. At large attack angles and low-speed abrasion, heat-resistant steels and heat-resistant austenitic-class steels are recommended. Among the tested materials, welded alloy C6,0Cr23Nb7Mo7W2Si2VT exhibited the highest resistance to gas-abrasive wear at normal temperature, characterized by the highest level of alloying and a volumetric fraction of strengthening phases. As the test temperature increased to 600 °C, its wear resistance decreased by 2.5 times, indicating inferior performance compared to the experimental alloy C2,8Cr14Ni6Mn6Mo3Ti2Nb2. The destruction processes of thin surface layers of alloys were studied using electron-ion microscopy, allowing us to assess the influence of their structural-phase composition on the mechanisms of high-temperature wear. The study of the wear characteristics of alloy C2,8Cr14Ni6Mn6Mo3Ti2Nb2 revealed that under the impact of abrasive, cracks form in the platelike carbides Me₃C₂ and Me₇C₃. However, the high ductility of nickel-alloyed austenite reduces the likelihood of splintering of the formed fragments. Additionally, fine compact carbides (Ti, Nb, Mo)_xC_y and Mo₂C restrain plastic deformation of the austenitic–carbide eutectic without causing destruction.

Tribological properties of titanium alloys VT22 and Ti-5553 are improved due to the chemical-thermal treatment of their surfaces and the application of a wear-resistant titanium nitride coating. The tribological properties were compared for samples without additional surface treatment, with surface modification by nitriding, with the titanium nitride coating, as well as with a two-stage treatment of sample surfaces, including primary nitriding of the surface followed by the application of a titanium nitride coating on it. It was found that low wear resistance is observed in titanium samples without coatings, while the wear resistance of samples with a nitrided surface layer increases for both types of tested alloys. Minimal wear occurs for the samples with two-stage formation of a titanium nitride coating while on samples without an intermediate nitrided sublayer, when tested with a ceramic ball, delamination of the coating is observed; the formation of the sub-layer prevents this type of destruction.

The results of research on the modernized SKI LX bench, which provides addition to the model fluid of various kinds of abrasive particles, the nature and properties of which can correspond to real operating conditions, are presented. In developing the program and methodology of these studies, used the after exploitation analysis of high-speed pumping units carried out at the fields of various companies in the Russian Fed-eration. The features of wear and the mechanisms of destruction of the working stages of the high-speed pump series 92ELNC85-2250-e2OE-10ETS were investigated. On a real design of a high-speed pump the possibility to determine the wear rate of tribo-contraction elements by the method of its weight determination with a forecast for the resource and to reveal the ways of its increase in a wide range of the number of suspended abrasive particles in the model fluid, and in particular, in water is shown. The results obtained in this work are the basis for the development of scientifically based methods for studying the wear resistance of bearing assemblies of high-speed centrifugal pumps in conditions of a wide variety of reservoir fluids and suspended particles contained in them.

The article considers the results of studies on the wear resistance of machine parts made of structural steels with nitrided layers obtained during complex surface preparation before ion implantation and subsequent ion nitriding. Nitrided layers on parts made of structural steels produced using traditional technology are not able to fully realize their potential for wear resistance, since oversaturation of grain boundaries with nitrogen leads to a decrease in the strength of their boundaries, the formation of a nitride grid and to the staining of grains and their fragments during wear friction. The method developed by the authors for activating the surface layer of parts by high-energy ion implantation treatment, in some cases, eliminates the process of nitride mesh formation. However, the microgeometric and physico-mechanical heterogeneity of the nitrided surface, as well as the presence of impurities on the surface, reduces the operational properties of the nitrided layer. It is shown that the use of dry electropolishing makes it possible to achieve the lowest surface roughness compared to other polishing methods, while ensuring the most homogeneous state of the surface layer material. It is also shown that the use of electroadsorption for surface cleaning makes it possible to eliminate impurities present on the surface of parts, which contributes to the most effective use of subsequent activation of the surface layer by high-energy ion implantation. It is also shown that as a result of the application of complex surface preparation of the part, it is possible to fully realize the possibilities of ion nitriding technology. Using the example of rotors of screw pumps operating under conditions of intense wear friction, the results of comparative wear tests are presented. It is shown that the use of complex surface preparation, including dry electropolishing and electroadsorption before activation of the surface layer by high-energy ion implantation increases the wear resistance of the nitrided layer by about 2 times.

The article considers the factors influencing the operation of a sliding bearing. It is shown that on the basis of the basic provisions of the theory of hydrodynamic lubrication, passing from the formula, characterising the bearing capacity of the lubricating layer of sliding bearings, to the parameters of the oil layer thickness and clearance, it is possible to obtain expressions for determining the functional clearances, in the range of which the bearing will operate under conditions of hydrodynamic friction. As a result, of calculations of the plain bearings of the conveyor drive gearbox, the maximum functional clearances had determined for the conditions of using bushings of various lengths in accordance with GOST ISO 4379–2006. The rational length of the plain bearing bush was selected based on the magnitude of the largest functional clearance and its influence on the deviation of the center distance in the gear drive of the gearbox. A new fit H8/f7 has proposed instead of those recommended by the GOST ISO 4379–2006 standard, which has guaranteed to ensure the presence of a hydrodynamic wedge at the beginning of operation and the most rational supply of materials for wear. The practical significance of the research lies in the possibility of using the proposed approach when designing sliding bearings operating under hydrodynamic lubrication conditions in order to determine the rational length and fit of the mating elements of the bearing unit.

The dependence of gear tooth wear on the angle of skew is investigated. It is noted that in gear mechanisms, due to elastic deformations of the elements, manufacturing and installation errors, the symmetry of the system's compliance is violated, and instead of nominal contact between the teeth, edge contact takes place. As a result, there is a concentration of stresses in the places of initial contact of the teeth, contact stresses sharply increase in these places, which in turn cause increased wear of the teeth in these zones. Because of this, the load capacity of the transmission is reduced, and the durability of the entire mechanism is also significantly reduced. From what has been said, it is important to establish the dependence of the wear value on the transmission load parameters, primarily on the angle of skew. The problem was solved using the method proposed in the paper using an elastic base model. In order to increase the accuracy of matching the specified model with the real picture, a bed with a variable base coefficient is used in the work. Formulas are obtained in closed form for the amount of wear as a function of the skew angle. Verification of these formulas according to the experimental data available in the literature has shown good convergence.

It was found that the misalignment significantly increases tooth wear. The results obtained can be useful in the design of gearboxes with cylindrical gears.

When developing materials for moving joints and friction units operating in outer space, the wear resistance of friction pairs with friction coefficients from 0.05 to 0.1 is of particular importance. The values of the friction coefficients determine the heating of the interfaces and the power of the drives. Wear resistance regulates the service life of friction units. The choice of diamond-like coatings as one of the elements of the friction pair determines the high wear resistance of the interface when working with solid lubricant coatings due to their high chemical inertness and the absence of substance transfer from the solid lubricating coating to the diamond-like coating. This paper presents the results of testing diamond-like coatings during friction on the solid lubricant coating EONIT-3 and tests in air and vacuum up to 10^–6 mm Hg. according to the shaftbushing scheme in the temperature range from –50 ℃ to +50 ℃. A diamond-like single-crystalline coating 20 microns thick was applied to a shaft made of hardened steel ShKh-15; EONIT-3 coating with a thickness of 15 microns is applied to a steel bushing. Tests were carried out under a normal load of 100 N; shaft rotation speed — 200 rpm; sliding speed — 0.12 m/s; test duration 1 hour. The friction coefficients and wear of the solid lubricant coating were measured. No wear of the diamond-like coatings was detected. The wear of the solid lubricant coating ranged from 1.065×10^–8 mm³/m to 3.195×10^–8 mm³/m at temperatures from –50 ℃ to +50 ℃ in air and in a vacuum of 10^–6 mm Hg.

The work examines the synergetic principles of fatigue fracture, which make it possible to identify the fundamental mechanical characteristics of materials and evaluate the kinetics of damage during the destruction of metals through critical parameters that control bifurcation points. In this case, fatigue failure is considered as a kinetic process depending on the order of supply of cyclic loading energy. Based on the principles of physical mesomechanics and synergetics, it is shown that the mechanical characteristics of a cyclically loaded tribocontact are important material parameters that determine the level of strain energy introduced in each loading cycle at each scaling level. It has been revealed that for practical purposes in tribocontacts it is necessary to ensure that the tension between the coating and the substrate corresponds to the maximum elasticity of the materials, according to the Griffiths criterion, and for viscous materials, a different value of the critical stress is considered — the Irwin-Oravan modification. Criteria for transient contact modes are given, considering that the coating must undergo changes in full agreement with the substrate when the system deforms under cyclic load. The research results in assessing the mechanical characteristics of materials of the coating-substrate system can be used as diagnostic signs in analyzing the development of damage to tribocontacts operating under cyclic fatigue loading conditions.