To improve the performance of heavily loaded friction units in technological machinery and transport vehicles, the use of multilayer CrAlSiN/Cr coatings has been proposed, in which Cr was employed as a sublayer and as an intermediate layer between the ceramic CrAlSiN layers. The coatings were deposited on 40KhN steel using a BRV600 vacuum system. The evaporation regime was a three-cathode arc process with magnetic separation. Two types of coatings were obtained, with total thicknesses of 1.25 µm and 3.6 µm. The microstructure of the coatings in cross-section was examined by scanning electron microscopy. The mechanical properties were characterized by instrumented indentation (continuous indentation method). Tribological tests were carried out using a ball-on-disk configuration. The surface morphology of the coatings after tribological testing was studied by optical profilometry. Owing to the periodic multilayer CrAlSiN/Cr architecture, the coatings obtained exhibited high hardness and favorable resistance to elastic and plastic deformation. An increase in the overall coating thickness and the number of alternating CrAlSiN/Cr lamellae ensures stable tribological performance (a friction coefficient of 0.5 at loads of 5—10 N) compared to the thinner variant (where the friction coefficient reaches 0.6—0.7). Coatings of the second type demonstrate a threefold decrease in wear rate compared to the thin coating over the entire load range of 1—10 N and with an increase in the number of cycles up to 1000, which confirms their substantially higher wear resistance. The stages and types of wear during interaction of the investigated coating with the corundum counterbody were identified, taking into account the obtained tribogram and the morphology of the wear tracks.

The relevance of studying the highly nonlinear processes of contact interaction between deformable bodies under conditions of non-limit equilibrium during the transition from a state of rest to sliding is demonstrated. A brief review of the results from studies on the phenomenon of pre-sliding displacement is provided. From the perspective of contact mechanics, the peculiarities of theoretical analysis of stress-strain state and wear under compression and compression with shear are discussed. An efficient method for solving the corresponding contact problems, based on the theory of variational inequalities and boundary element discretization of the contact region, is presented.

It is concluded that considering frictional contact as an inhomogeneous surface region consisting of slip zones and stick ones, where tangential displacements are zero, has undoubted fundamental importance for the tribology and mechanics of deformable solids. This is expressed in the correct resolution of the wellknown Painlevé paradox, the mechanical and mathematical interpretation of phenomena of limit equilibrium at friction and in calculated predicting of new effects of contact interaction between bodies made of metamaterials with special (programmable) deformation properties.

The practical significance of this research consists in the possibility of computer-aided design optimization of friction gears and conditionally fixed connections; refining the results obtained during mechanical testing of materials; improving technological methods of material forming (forging, rolling, stamping, and pressing); as well as predicting geomechanical (seismic) events, which are characterized by a state of limit equilibrium in friction.

The results of a study examining the influence of polymer phase type on the tribological characteristics of metal-fluoroplastic material based on bronze are presented. It is shown that pressure sintering is the optimal method for obtaining the material. The tribological characteristics of a porous bronze layer not impregnated with fluoroplastic are significantly lower than those of an impregnated one. The friction coefficient is

2.4 times higher than that of a bronze layer impregnated with F-3M fluoroplastic and 3 times higher than that of a bronze layer impregnated with Hostaflon TF 4406 fluoroplastic. Wear resistance is two and five times lower, respectively. The friction coefficient of the antifriction layer made of porous bronze impregnated with F-3M fluoroplastic is 0.22, while that of Hostaflon TF 4406 is 0.17. Wear in the first case is three times greater than in the second. The friction mechanism of materials was studied, showing that wear of a porous bronze layer is accompanied by plastic deformation of bronze particles, oxidation of their surface layer, and reduction of porosity. Wear of a porous bronze layer impregnated with F-3M fluoroplastic results in wear and chipping of the fluoroplastic, exposure of bronze particles, and the incorporation of wear products into the polymer phase. Wear of a porous bronze layer impregnated with fluoroplastic results in virtually no wear of Hostaflon TF 4406 fluoroplastic, with a uniform, fine-grained, and non-porous friction surface structure.

This paper describes the design of a metal-polymer cargo sled intended for towing over a surface composed of a mixture of snow and ice with scattered rock inclusions. Several key factors were considered during the vehicle development. A standard plastic pallet, mass-produced and originally designed by the IMMS of the National Academy of Sciences of Belarus, served as the base for the sled cargo platform. Manufactured from a blend of low-density polyethylene, high-density polyethylene, and polypropylene, the pallet offers high strength and load-bearing capacity across a wide operating temperature range from minus 60 °C to +80 °C. Metal runners with a polymer sliding layer are used to reduce friction and wear during the operations of the Belarusian Antarctic Expedition in the coastal zone of East Antarctica (Enderby Land). The design of the runners ensures low material consumption, the necessary rigidity, and a low coefficient of friction during operation. The sled was tested in Antarctica during the 2024—2026 seasons and demonstrated good operational performance.

The aim of the work is to increase the wear resistance and improve the tribotechnical characteristics of PTFE–based metal polymer composites filled with nanoscale ZrO₂ by optimizing sintering conditions and identifying the mechanisms of transfer film formation.

PTFE composites with a content of 8 wt. % ZrO₂ was obtained with cold pressing (80 MPa) followed by sintering at 360 °C and holding for 20 min and 9 min per 1 mm section. Tribological tests were carried out according to the “finger–disk” scheme under friction conditions without lubricant, at a sliding speed of

0.75 m/s and a load of 2 MPa. The microstructure and elemental composition of the transfer films were studied using scanning electron microscopy and energy-dispersive spectroscopy.

It was established the reducing the exposure time to 9 min/mm reduces the wear rate to 0.4 mg/h (500 times lower than that of unfilled PTFE) and decreases the friction coefficient from 0.35 to 0.11. Prolonged exposure (20 min/mm) causes residual thermal stresses and leads to abrasive wear with the formation of grooves up to 159 μm wide. EDS analysis of the steel counterbody showed that at a rate of 9 min/mm, a denser and more stable transfer film is formed, with an increased oxygen content (6.43 % versus 2.54 % at 20 min/mm) and zirconium content (3.78 % versus 0.03 %). ZrO₂ nanoparticles provide directed heat dissipation from the contact zone, preventing thermal softening and plastic deformation of the polymer matrix. Optimal sintering conditions (9 min/mm) ensures the formation of a durable oxide-metallic transfer film that protects the counterbody from catastrophic wear. The recommended running-in period is about 6,000 s.

The study examined methods for determining the friction coefficient in metal forming processes, using a universal friction testing machine for this purpose. An assessment was made of the feasibility of determining the friction coefficient by this method for cold tube rolling in cold pilgering mills. The studies were carried out for two versions of cooling lubricants: No. 1 — emulsion, machine oil + water (50/50 %); cooling lubricant No. 2 — composition of cooling lubricant No. 1 + complex lithium grease containing 1.5 % nanodiamonds (50/50 %). During the experiments with cooling lubricant No. 1, we obtained the repeatability with a high degree of reliability. The recommended friction coefficient value for cooling lubricant No. 1 is λ₁ = 0.13, which falls within the range of friction coefficients reported by other researchers for this metal forming process. Experiments conducted with cooling lubricant No. 2, when reproducing the test, showed that the resulting dependence diagrams exhibit a completely different pattern of friction coefficient variation as a function of test duration, explainable by the segregation of nanodiamond additives, which is difficult to predict when mechanically adding a plastic grease modified with nanodiamond additives to the cooling lubricant No. 1 followed by mixing, but hereby, the initial friction coefficient values across different diagrams differed by no more than ± 2.150 % and lay within the range of 0.263. Thus, the method for determining the friction coefficient developed by the authors is also applicable to cold pilgering.

The aim of the work is to theoretically substantiate the application of the tribospectral identification method of friction processes on a laboratory bench for tribological testing of samples with ion-plasma composite coatings, which allows varying the vibration effect on the tribocontact with specified amplitudes and oscillation frequencies, which allows for a comparative analysis of energy dissipation in the triboconjanction. Mathematical modeling was carried out, and the elastic and inertial, and dissipative parameters of the tribosystem (the friction pair “sample – counterbody”) were determined by varying the stiffness and damping of the composite coating. The formulated requirements for the bench are that for greater likelihood of identification of the friction and wear processes in the friction pair “sample – counterbody”, the software and hardware complex of the bench provides for the analysis of variations of the generalized coordinates in a wide range of frequencies from 0 kHz to 20 kHz as the load on the sample, the resistance torque, and the additional vibrator, providing external excitation of the tribocontact from the mechanical subsystem.

The article presents the results of comparative analysis of composite coatings of frictional and antifriction samples based on tribospectral identification of friction processes and assessment of energy dissipation. The study of friction application samples is implemented at a maximum resistance moment of 20 N∙m for laboratory friction machines, and the study of antifriction application samples corresponds to boundary and liquid friction (respectively, with a friction coefficient of μ = 0.15 and 0.05). The boundary conditions for the research are the minimum and maximum levels of the dimensionless damping coefficient of the tribosysteme. ξk(1) = 0.001 (boundary friction or mechanical characteristics of coatings with a low energy dissipation value) and ξk(2) = 0.707 (fluid friction, or coatings with a higher energy dissipation value), which corresponds to the decrement of damped oscillations χ_k⁽¹⁾ = 1.006 and χ ⁽²⁾ = 535.5, respectively.

At present, nomographic methods are increasingly used in engineering practice. As a highly convenient computational tool for calculations based on ready-made formulas, nomograms make it possible to significantly reduce calculation time and quickly solve required problems with sufficient practical accuracy. The main advantage of nomograms as a computational apparatus is the speed of calculations. Another important benefit is that they allow one to quickly obtain a numerical solution of a nomographed equation with respect to any variable involved and to flexibly vary input data in order to obtain the desired result in the required units. In most cases, using a nomogram only requires careful reading of the instructions provided in the text or even just studying the usage diagrams presented on the nomogram sheets.

The article analyzes the application of practical nomography in various engineering, scientific-technical, and technological calculations. Methods of practical nomography are considered for processing research results aimed at determining the optimal properties of multifunctional polymer composite lubricants. The paper describes the use of Gibbs triangles for analyzing the required characteristics of composite lubricants and shows that practical nomography methods make it possible, with sufficient accuracy, to select the concentrations of components in multicomponent lubricants depending on their properties.

This article explores the use of periodic surface micro-texturing as a passive method for controlling sliding friction.

Using a plain journal bearing of a multistage centrifugal pump as an example, computational fluid dynamics modeling and computer-aided design are used to examine the parametric optimization of surface micro-texturing geometry in the form of discrete elliptical dimples to reduce the friction coefficient in a rotorbearing system.

The friction coefficient of the smooth surface corresponded to the hydrodynamic lubrication regime. Under single-factor variation of the parameters, the change in the objective function did not exceed 2 %. The identified relationships were nonlinear: with increasing ellipse axis lengths L and H (the area occupied by the texture), the friction coefficient decreased and tended exponentially toward a threshold value, whereas with increasing depth D it passed through a minimum. The minimum with respect to depth arose from the competition between the decreasing adhesion and increasing deformation components of friction, vortex formation at the dimple inlet, and the hydrodynamic-wedge effect; the parameter H (the minor axis of the ellipse) had the largest influence. The optimal configuration (D = 63 µm, L = 250 µm, H = 150 µm) reduced the friction coefficient by 6.18 % relative to the smooth surface.

Thus, using periodic surface micro-texturing technology, it is possible to both reduce and increase the friction coefficient, which can be applied in a variety of technical applications.

The article considers the determination of the effect of material properties and surface irregularities of a wood-metal composition on the wear resistance and friction pairs used in components of timber-processing and general machine-building machinery.

Experimental studies have been performed for various types of wood-metal bushings, differing in composition, method of modification of the wood matrix and the nature of the distribution of metal inclusions. Tribological tests were carried out according to the “shaft–sleeve” scheme with an abrasive-oil layer for 80 hours; at a load of 50 N; rotation speed of 25 min^–1; axial displacement speed of the countersunk shaft 0.01 m/min. Wear resistance was assessed by the operating time, before the shaft jamming.

A quantitative assessment of tribotechnical characteristics in rotational and combined modes of motion has been carried out. Regression analysis was performed, which made it possible to establish a relationship between the intensity of wear and the hardness of the surface layers. It has been established that under startup and stop conditions, wear is mainly realized by the mechanism of waterjet and deformation destruction of the surface layers of the composite material, since the insert and shaft are separated by a gap filled with a lubricating fluid during operation. For wood-metal sliding bearings that do not contain implanted particles, the most rational roughness is R_a = 0.4—1.6 mm, which reduces the likelihood of cutting the wood composition. For bearings containing implanted particles, which can become abrasive during the painting process, a roughness close to the value of R_a = 3.2 mm is the most rational.