Problems of Tribology = Проблеми трибології - 2025 рік
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Документ Enhancement of corrosion–mechanical wear resistance of metallic alloys by glow-discharge nitriding(Хмельницький національний університет, 2025) Stechyshyn, M.S.; Mashovets, N.S.; Pidhaichuk, S.Ya.; Shevchuk, V.М.; Korinnyi, А.V.The aim of this work is to provide a comprehensive analysis of hydrogen-free nitriding and nitrocarburizing processes in a glow discharge, to summarize the regularities of nitride and carbonitride layer formation on steels and titanium alloys, and to evaluate their corrosion–mechanical wear resistance under conditions of sliding, fretting, cavitation, and exposure to aggressive media. Particular attention is given to the application of Pastukh’s I.M. model for interpreting the kinetics and energy mechanisms of diffusion processes. The study presents a comparative analysis of the structural–phase transformations during nitriding and nitrocarburizing in a hydrogenfree glow discharge and systematizes experimental data on microhardness, electrochemical behavior, and corrosion–mechanical wear resistance. The methodological basis of the theoretical part is the energy-exchange model developed by I. M. Pastukh, which describes the influence of active plasma species on the diffusion rate and phase formation. It is shown that hydrogen-free nitriding provides intensified nitrogen diffusion, the formation of stable nitrides TiN, Ti₂N, ε-(Fe₂– ₃N), γ′-(Fe₄N), and the elimination of hydrogen embrittlement. It is established that nitrocarburizing produces multilayer carbonitride structures with hardness values of 900–1300 HV and high adhesion to the substrate. The modified layers demonstrate a 3–6-fold increase in wear resistance, a 2.5–4-fold reduction in cavitation damage, and a significant decrease in corrosion current in NaCl and NaOH solutions. A transition of the dominant failure mechanisms from brittle and adhesive to plastic-deformation dominated modes has been identified. The obtained results confirm the experimentally observed regularities of carbonitride-layer formation and demonstrate the key role of ion bombardment in generating the defect-subzone that governs diffusion kinetics and phase stability. The findings may be applied in the design of wear-resistant machine components, medical implants, and elements of cavitation units operating in alkaline and chloride environments. Hydrogen-free nitriding and nitrocarburizing technologies are identified as highly efficient, economically feasible, and suitable for industrial implementation.Документ Theoretical foundations of glow discharge nitriding of internal local recesses on metallic surfaces(Хмельницький національний університет, 2025) Stechyshyn, M.S.; Dykha, O.V.; Skyba, M.Ye.; Zdorenko, D.V.; Liukhovets, V.V.This paper presents a comprehensive analysis of internal local recesses on metallic surfaces during glow discharge nitriding. Various types of recesses and their geometric features are studied to evaluate their impact on electric field concentration, which in turn affects the uniformity of surface modification. A field concentration criterion is introduced to quantify these effects, and an analytical framework is developed to describe the relationship between surface geometry and electric field parameters. The influence of the dimensions of internal recesses on field concentration is examined using numerical simulations. The results provide a deeper understanding of the mechanisms leading to localized variations in current density distribution on nitrided surfaces. The developed analytical tools are applicable for predicting and controlling electric field concentration indicators in glow discharge processes used for the surface modification of metallic components, which is critical for ensuring optimal mechanical and tribological properties.Документ Analytical study of a hydraulic drive model for a municipal waste container overturning mechanism in a garbage truck considering the wear of friction pairs(Хмельницький національний університет, 2025) Bereziuk, O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Ivanov, S.Cv.; Yavorskyi, V.Ye.The article is dedicated to the analytical study of the improved mathematical model of the hydraulic drive of the mechanism for overturning a container with municipal solid waste into a garbage truck, taking into account the wear of friction pairs. As a result of the analysis of the performed numerical studies of the nonlinear improved mathematical model of the hydraulic drive of the mechanism for overturning a container with municipal solid waste into a garbage truck, taking into account the wear of friction pairs, a linearized version of this model was developed in the form of a system of ordinary linear differential equations of the 2nd order. To carry out design calculations of new garbage truck designs, approximate analytical dependencies were obtained for the pressure in the hydraulic cylinder pressure line, the angular velocity and the angle of container overturning on time were obtained based on the proposed linearized mathematical model of the hydraulic drive of the container overturning mechanism in the technological operation of loading municipal solid waste into the garbage truck during the 1st phase – overturning the container to the equilibrium position, taking into account the wear of friction pairs. A regression equation was obtained, which allows to approximately determine the duration of the 1st phase – the rotation of the container to the equilibrium position during its overturning in the technological operation of loading municipal solid waste into a garbage truck, taking into account the wear of friction pairs, which can be used during design calculations of new garbage truck designs taking into account the wear of working bodies without the need to study the nonlinear mathematical model of the drive, as well as during optimization of the main parameters of the hydraulic drive. It was established that the analytical study of the linearized improved mathematical model of the hydraulic drive of the mechanism for loading municipal solid waste into a garbage truck, taking into account the wear of friction pairs during the 2nd phase – pouring waste from the container into the body of the garbage truck requires further research.Документ Self-lubricating glass composite magnesium carbide nanocoating(Хмельницький національний університет, 2025) Shchepetov, V.V.; Fialko, N.M.; Bys, S.S.The results of the study of the friction and wear characteristics of the developed nanostructured glass composite self-lubricating coatings are presented, the structural components which through magnesium carbide have a qualitative effect on the graphitization process due to the formation of a surface layer of carbide α-graphite, which, when combined with surface oxides characterized by low shear resistance, performs the role of solid lubricants under friction conditions. The positive role of the glass phase in the form of aluminoborosilicate, which affects the tribotechnical properties of coatings, has been established. It has been determined that the increase in adhesion strength is achieved by forming a surface layer of vitreous sodium silicate during spraying. It has been found that the intercalation of the graphite layer with dispersed particles of the surface structure does not significantly affect the tribotechnical characteristics. The developed nanostructured glass composite coatings showed high antifriction characteristics.Документ Research on the influence of rolling element geometry on the wear resistance of drilling equipment bearings(Хмельницький національний університет, 2025) Makovkin, O.; Dykha, O.; Valchuk, I.; Kalaczynski, T.The article presents the results of experimental studies of the influence of the geometric parameters of rollers and raceways on the resistance of roller bearings to rolling element rotation and jamming. Failure of bearing assemblies due to roller rotation is a common cause of emergency equipment shutdown, which is accompanied by expensive repairs. The aim of the work was to determine the optimal ratio of roller length to its diameter (l/d) and the influence of raceway diameter (D) on critical wear, which leads to loss of roller stability. The research methodology was based on mathematical experimental design with variation of parameters l, d and D in laboratory conditions when simulating misalignment of the bearing assembly. An empirical relationship was established that quantitatively describes the relationship between roller geometry, raceway diameter and critical wear. The results showed that increasing l/d increases the resistance of the rollers to turning, while an excessive increase in D contributes to the growth of backlash and distortions. The most effective configuration was found to be the one with the maximum length and minimum diameter of the roller at a small value of D. The results obtained can be used for the design improvement of bearing assemblies, in particular in drilling equipment, in order to increase the resource and reliability of their operation.Документ The influence of hydrogen saturation on the wear mechanism of steel(Хмельницький національний університет, 2025) Shchepetov, V.V.; Bys, S.S.; Byalik, M.R.; Medvedchuk, V.Yu.; Bys, Ya.S.The tribological characteristics of hydrogenated steel 60C2 with different structural states were compared with the obtained results of studies of friction surfaces by physicochemical methods, which allowed us to draw a conclusion about the relationship between friction and wear indicators with the processes occurring on the surface of the material during friction, and the significant influence of hydrogen present in the contact zone on them. It was proven that during friction on the contact surface of hydrogenated steel 60C2, regardless of its structural state, the process of formation of secondary structures occurs, which determine the process of friction and wear of the material. Reduction of the wear intensity of steel 60C2 with a tempered martensite structure (300C) is accompanied by the formation of secondary structures on the surface, which have a higher resistance and shield the base material from direct contact and destruction. In addition, the saturation of the material with hydrogen changes the nature and mechanism of formation of secondary structures, which in turn leads to a change in the mechanism of friction and wear of the material.Документ Improved mathematical model of the hydraulic drive of the garbage truck’s sealing plate mechanism taking into account the wear of its hydraulic cylinder(Хмельницький національний університет, 2025) Bereziuk, O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Alekseiev, A.Ye.This article is dedicated to the improvement of the mathematical model of the hydraulic drive of the mechanism of the garbage truck’s sealing plate, taking into account the wear of the hydraulic cylinder. An improved nonlinear mathematical model of the operation of the hydraulic drive of the garbage truck’s sealing plate mechanism is proposed, which takes into account the wear of the hydraulic cylinder and allows to numerically study the dynamics of the drive and determine that taking into account the wear of the hydraulic cylinder significantly affects the main parameters of the hydraulic drive of the garbage truck’s sealing plate mechanism. This study of the mathematical model was carried out using the fourth-order numerical Runge-Kutta-Felberg method with an adaptive integration step. Graphical dependencies were plotted to compare changes in the main parameters of the hydraulic drive of the garbage truck’s sealing plate mechanism without taking into account the wear of the hydraulic cylinder and with taking into account the wear. It has been established that the creation of a linearized mathematical model of the hydraulic drive of the garbage truck’s sealing plate mechanism, taking into account the wear of the hydraulic cylinder, and its analytical solution in order to obtain dependencies for an improved methodology for engineering calculations require further research.Документ Probabilistic approach to assessing tribotechnical reliability indicators of friction units(Хмельницький національний університет, 2025) Dykha, M. O.; Dytyniuk, V. O.; Staryi, A. L.The article presents a theoretical and analytical review of the probabilistic approach to assessing the tribotechnical reliability of mechanical systems, in particular friction units. The influence of the random nature of loads and wear on the reliability of machine elements is considered. The feasibility of using distribution functions and probability density functions to describe the wear process is substantiated. Mathematical models are described in detail that allow determining the probability of element failure for given statistical characteristics of the load and permissible wear. Both constant and block load conditions are taken into account. The results of the study can be used in the design and operation of highly reliable tribotechnical systems, as well as for predicting their resource under conditions of operational uncertainty.Документ Analysis of the influence of radial clearance in a bearing on its operating modes, taking into account mass and magnetic imbalance of the induction motor rotor(Хмельницький національний університет, 2025) Goroshko, A.; Zembytska, M.The article studies the problem of the journal motion of a three-phase induction motor rotor in a bearing. A simplified model of the journal motion is studied at the moment of journal separation and transition from the pendulum mode of journal motion to the impact mode. In this case, the elastic-damping properties of the bearing and the final rigidity of the rotor are ignored. The model takes into account the eccentricity of the rotor mass and the radial internal clearance of the bearing. In addition, the forces of unbalanced magnetic pull (UMP) caused by the magnetic eccentricity of the induction motor rotor, which is caused by the radial clearance of the bearing, are taken into account. It is analytically shown that the forces of UMP cannot be ignored, since even the rated clearance of bearings of low- and medium-power motors causes an unbalanced force commensurate with the force caused by the eccentricity of the mass. Using numerical modeling and simulation for a three-phase induction motor with a squirrel-cage rotor with a power of 11 kW and a speed of 3000 rpm, the dependences of the critical frequency of the journal separation from the bearing for different values of the mass eccentricity and radial clearance are presented. It is shown that without taking into account the UMP, an increase in the radial clearance leads to a decrease in the critical separation speed. In this case, a bearing with a passport radial clearance is able to switch to the mode of periodic impacts of the journal at a speed lower than the nominal speed of rotation of the rotor with an acceptable eccentricity. Taking into account the UMP, on the contrary, it significantly increases the value of the critical separation speed. At the same time, it is necessary to take into account that with an increase in UMP, the radial load on the bearing also increases, which in turn leads to increased wear of the bearing.Документ Wear resistance of structural steels carbonitrated by the separate method(Хмельницький національний університет, 2025) Stechyshyn , M.S.; Dykha, O.V.; Zdorenko, D.V.; Oleksandrenko, E.G.The article investigates the influence of technological modes of separate carbonitriding of carbon steels on the thickness and microhardness of the hardened layer. Two hardening variants were investigated: first, carburizing of surfaces was carried out in argon-propane, and then nitriding in argon-nitrogen mixtures and vice versa. As the conducted studies have shown, the variant of the hardening technological process significantly affects the physical and mechanical characteristics of the hardened layer. In all two variants of the technological process, the hardened layer consists of a surface carbonitride zone and a diffusion zone of internal nitriding, but the properties of these zones are different in different variants of the technological process. Thus, when hardening steels according to the first mode, the thickness of the carbonitride zone is maximum, and the internal nitriding zone has a small thickness. This is explained by the fact that the carbonitride layer created on the steel surface at the first stage of processing performs the function of shielding the surface from the penetration of nitrogen ions into the surface layer of the metal. When hardening according to the second mode, the carbonitride zone has a slightly smaller thickness, but a more developed internal nitriding zone. In addition, carbonitriding according to the first mode leads to the formation of carbonitride inclusions in the diffusion zone in the form of a mesh, which significantly reduce the plasticity of the layer and under dynamic loads are centers of microcrack nucleation. It has also been established that a carbonitride ε − phase is formed on the surface of steels, which consists of carbonitrides of the type Fe2(N,C), Fe3(N,C), Fe4(N,C). The carbonitride zone has high hardness, high corrosion resistance, and increased wear resistance. The thickness of the carbonitride zone reaches a thickness of up to 25 microns. Under the carbonitride zone is the internal nitriding zone, which has a large thickness and is the main part of the carbonitrided layer. The internal nitriding zone consists of a nitrogenous solid solution of the base metal, its nitrides and nitrides of alloying elements. The dependences of thickness and microhardness on the technological parameters of carbonitriding of carbon steels obtained in the work: temperature, saturation time, composition of the gas medium, its pressure allow them to be optimized depending on the requirements of further operationДокумент Improving the wear resistance of guides: tribological analysis, surface texture and lubricants(Хмельницький національний університет, 2025) Dykha, O.V.; Dytyniuk, V.O.; Kovtun, O.S.; Fasolia, V.O.; Hetman, M.V.The article considers the main failure modes of guides, in particular wear and contact fatigue, which depend on friction between contact surfaces. The influence of tribological parameters, in particular surface roughness and lubricating structures, on the operational characteristics of linear guides is studied. Particular attention is paid to the dynamic behavior of guides, which determines the accuracy and stability of mechanical systems. To predict wear, mathematical models based on the Archard and Hertz theories were used, which allow estimating load distribution and contact deformations. The influence of lubricants, in particular molybdenum disulfide and hexagonal boron nitride, on reducing the friction coefficient and improving antifriction properties was separately studied. The prospects for using new materials, such as cubic boron nitride, to increase the wear resistance of guides are considered. Methods for optimizing the load between rolling elements, which contributes to increasing the durability of guides, are proposed. The results obtained can be used to improve the designs of high-precision mechanical systems and reduce operating costs.Документ Tribotechnical properties of coatings based on magnesium compounds(Хмельницький національний університет, 2025) Shchepetov , V.V.; Fialko , N.M.; Bys, S.S.The article summarizes the results of studies of tribotechnical properties of detonation coatings based on magnesium orthosilicate under conditions of constant load in the sliding velocity field. The structural and phase composition of the coatings was studied using modern physical analysis methods. The developed and studied coatings based on magnesium orthosilicate have high and stable antifriction properties in the entire load-velocity range of tests. It is emphasized that the result of antifriction under friction conditions is the additive effect of both the carbide graphite film and dispersed surface oxide structures, the synthesis of which provides modification of the surface of the structure, which is capable of self-lubrication and at the same time limits the development of unacceptable destruction processes.Документ Improved mathematical model of the operation of hydraulic drives of garbage truck mounted sweeping equipment with regard to the wear of a cylindrical brush(Хмельницький національний університет, 2025) Bereziuk , O.V.; Savulyak, V.I.; Kharzhevskyi, V.O.; Harbuz, Ye.S.The article is dedicated to the improvement of the mathematical model of operation of hydraulic drives of mounted sweeping equipment of a garbage truck, taking into account the wear of a cylindrical brush. An improved nonlinear mathematical model of the operation of hydraulic drives of mounted sweeping equipment of a garbage truck that takes into account the wear of a cylindrical brush, is proposed, which allowed to numerically study the dynamics of these drives during startup and determine that taking into account the wear of the cylindrical brush significantly affects such values as the pressure at the inlet of the hydraulic motor of the cylindrical brush and the angular velocities of both hydraulic motors. At the same time, the pressure at the inlet of the screw conveyor hydraulic motor after taking into account the wear of the cylindrical brush has hardly changed. The study of this mathematical model was carried out using the numerical Runge-Kutta-Felberg method of the 4th order with a variable integration step. It was also established the graphical dependencies to compare changes in the main parameters of the hydraulic drive of the garbage truck’s mounted sweeping equipment during startup without taking into account the wear of the cylindrical brush and with taking into account the wear. It has been established that the creation of a linearized mathematical model of the operation of hydraulic drives of garbage truck mounted sweeping equipment, taking into account the wear of a cylindrical brush, and its analytical solution in order to obtain dependencies for an improved methodology for engineering calculations require further research.