Problems of Tribology

Lifetime improvement of contact brush units of automotive power machines. Part 1

A. H. Dovhal — 2025-03-22

Lifetime improvement of contact brush units of automotive power machines is suggested. Particularities of mass transfer of aluminium electrode on copper substrate is researched. The structure of aluminium electrospark coating on copper substrate is investigated. The fine dispersed eutectic structure with copper-aluminium solid solutions of electrospark coating is detected. This structure is suitable for good coating conductance and well coating adhesion for high speed application under electric current like a contact brush unit of alternators or commutator unit of power starters.

Analysis of damage to ceramic balls in hybrid rolling friction pairs

R.E. Kostunik — 2025-03-22

Most bearings are currently made primarily from steel, but they fail relatively quickly under high loads, temperatures, as well as abrasive, corrosive, chemical and other types of wear. Replacing steel balls with ceramic balls, i.e. creating hybrid bearings, in many cases allows achieving significantly higher performance and expanding the range of functionality of the devices in which they are used. For example, hybrid ball bearings take advantage of ceramic rolling elements with high quality surface treatment of steel rings, which allows for longer service life and better performance at high rotational speeds. As practice shows, hot-pressed silicon nitride (Si₃N₄) is the main material used to create hybrid bearings with ceramic rolling elements, although there is also interest in materials such as boron carbide (B₄C), silicon carbide (SiC) and aluminium oxide (Al₂O₃). However, there are no publications devoted to the analysis of the causes of formation and accumulation of damage to ceramic balls in hybrid rolling friction pairs. Therefore, the aim of the study is to determine the mechanism of formation and development of surface damage in ceramic balls of hybrid rolling friction pairs.

Improvement of physical and mechanical characteristics of gearbox shafts using the oxycarbonitriding method

Yu. Ye. Meshkov — 2025-03-22

The article investigates the issue of promising methods for improving steels by modifying surface layers with the application of protective coatings. Priority areas of scientific research in the field of mechanical engineering have been identified for the development of new methods and technologies for increasing the wear resistance of steel surfaces by applying modified diffusion coatings. It has been shown that the key problem in optimizing the processes of saturation of metals and alloys with one element is cementation, nitriding, alitization, chromium plating, etc. Saturation with two or more elements is used very limitedly. The features of chemical-thermal treatment of steel are considered, with the help of which we have the opportunity to obtain a material characterized by increased characteristics and properties (surface hardness, corrosion resistance, wear resistance). Based on the identified features of coatings in terms of composition, structure, and properties, chemical-thermal treatment methods can be promising when operating them under wear conditions. However, the proposed innovative metallization method – oxy carbonitriding – can compete with these technologically complex processes. It was established that combined chemical-thermal treatment allows to increase the corrosion resistance of the material, the longer the oxycarbonitriding process time, the thicker the oxycarbonitrided layer.

Interrelation of the volume temperature of modified oils and local temperatures in the friction contact zone under extreme operating conditions

O. Milanenko — 2025-03-22

A methodology has been developed that allows, using the temperature criterion, to determine the thermomechanical stability of oils and, thus, to analyze the modification of oils to improve the lubrication efficiency and wear resistance of friction pairs of conformal internal combustion engine units operating under extreme conditions. The correlation relationship between the temperature in the local frictional contact zone and the bulk temperature of the modified oil was determined with an increase in the maximum contact stress during the running-in period with a corresponding shift of the correlation linear dependences towards high temperatures. Under conditions of operation up to 15 cycles, increased thermomechanical stability of the modified oil was established in comparison with the standard oil, which confirms the optimal structural adaptability of the modified layers to extreme operating conditions.

Wear resistance of structural steels carbonitrated by the separate method

M.S. Stechyshyn — 2025-03-22

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.

Іnfluence of tribotesting on microhardness of polymers

R.M. Marchuk — 2025-03-22

This study investigates the microhardness of the polymeric material Zedex zx-100k and other polymers following tribological testing at different sliding speeds. The primary objective of this research is to select polymers for potential use in composite materials. Microhardness was determined using a ПМТ-3 microhardness tester by indenting diamond indenters into samples in various zones – on the initial surface of the material and in the wear area. The results obtained allow evaluating the influence of sliding speed on the change in microhardness of the polymeric material and its behavior under wear conditions. Additionally, the results enable comparison of different polymers tested on a tribometric setup with subsequent assessment of their physical characteristics. The research highlights the importance of understanding the tribological properties of polymers, as these materials are increasingly being used in various industrial applications due to their favorable characteristics, such as low weight, cost-effectiveness, and chemical resistance. The selection of suitable polymers for composite materials is crucial for enhancing the performance and durability of products in which these materials are used. Moreover, the study provides insights into the mechanisms of wear and the role of microhardness in the wear resistance of polymers.

Improving the wear resistance of guides: tribological analysis, surface texture and lubricants

O.V. Dykha — 2025-03-22

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.

Analysis of the causes of damage to centrifugal pumps during operation and methods of their elimination

I.V. Morshch — 2025-03-22

The paper reviews the research on improving the efficiency of operation and service life of centrifugal pumps, which are widely used in machinery for pumping various liquids. The main reasons for the failure of centrifugal pumps, as well as modern approaches to their prevention, are considered. It is established that increasing the efficiency of pump operation can be achieved by analyzing, modeling and optimizing their design. It was found that modeling the operation of smaller pump models and comparing surrogate models with the original ones is a modern, highly effective method of optimizing pump performance. The important role of protective coatings in increasing the wear resistance of parts is established, and the experience of introducing innovative coating technology at enterprises is described.

Physical and chemical processes in the application of antifriction coatings by the friction-mechanical method

A.M. Krasota — 2025-03-22

The current models of antifriction coating formation by finishing antifriction non-abrasive treatment has shown the lack of a thorough analysis of physical and chemical processes occurring in the friction zone. From this point of view, it seems reasonable to study the process of coating formation at the stages of surface activation, deposition of antifriction components and formation of an antifriction coating. The considered characteristic structures for each of the stages of antifriction coating application and chemical reactions that occur during the formation of an antifriction coating allow us to track the processes accompanying the formation of coatings and identify ways to improve them. It is proved that the quality of coating formation directly depends on the material of the part and tool, temperature in the deposition zone, material diffusion rate, and dissociation of chemical compounds. A physical model of the process of finishing antifriction treatment is proposed, which determines the chemical reactions and physical processes occurring at different stages of the coating formation. The analysis of the model allows to find out the characteristic phenomena in the system ‘part – tool – technological environment’, and to influence the quality of the formation of an antifriction coating by the friction-mechanical method.

Research on thermoplastics under impact-abrasive wear

A. Gypka — 2025-03-22

The article presents the results of research into the regularities of friction processes and impact-abrasive wear of thermoplastics under cyclic and shock loads. The conditions and modes of operation of gas transportation equipment units and the reasons for the failure of the most loaded parts are analyzed in detail. The nature of the impact of the abrasive and its characteristics on the wear resistance of the working surfaces of parts of gas transportation equipment units is revealed. The choice of thermoplastic grades for the manufacture of parts of gas transportation equipment working units that operate under cyclic shock loads is justified. The designs of existing stands for the study of surface deformation and impact-abrasive wear of thermoplastics are analyzed. The design of the experimental stand is improved and a force loading mechanism is manufactured to implement the tasks set, a comprehensive research methodology is proposed. The influence of the parameters and conditions of cyclic impact loading on the wear resistance of thermoplastics under conditions of impact-abrasive wear are identified and substantiated. Practical recommendations have been developed regarding the possible use of the studied thermoplastics for the manufacture of parts for gas transportation equipment assemblies.

Tribotechnical properties of coatings based on magnesium compounds

V.V. Shchepetov — 2025-03-22

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

Improved mathematical model of the operation of hydraulic drives of garbage truck mounted sweeping equipment with regard to the wear of a cylindrical brush

O.V. Bereziuk — 2025-03-22

The article is dedicated to the improvement of the mathematical model of operation of hydraulic drives of mounted sweeping equipment of a garbage truck. 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 4^th 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 equipment during startup without taking into account the wear of the cylindrical brush and with taking into account the wear.

Research on the technological process of restoration with electrodiffusion strengthening of the working surfaces of the segments of the headers of combine harvesters

D.D. Marchenko — 2025-03-22

The paper presents a study of the technological process of restoring the working surfaces of combine harvester header segments using electrodiffusion strengthening (EDS). The EDS of restored Duracut Knife Sections was experimentally investigated. With a current density the ratio between the hardness of the front and rear surfaces of the blade was observed . The relative wear resistance of the restored segments with EDS hardening was on average 1.3 times higher than that of new segments. Quantitative microanalysis of the chemical composition across the cross-section of the EDS-treated segments revealed an increase in the concentration of alloy-forming components in the hardened surface by 1.2 times. As a result of diffusion segregation, the concentration of elements increased. Larger values were observed on the rear surface of the restored segment's blade. A technological process for restoring the working surfaces of the Duracut Knife Sections of the John Deere combine harvester header using EDS has been developed. The proposed technology allows for the restoration and strengthening of the working surfaces of segments in grain harvesting and forage harvesting combines, as well as mowers. For the EDS-hardened segments, the blade thickness were maintained after the operational tests, indicating the presence of the self-sharpening effect.

Selection of informative acoustic emission parameters for determining the wear rate of woodworking equipment in transient modes

A.V. Voitov — 2025-03-22

The directions of application of the acoustic emission method for the study of transient processes in tribosystems are considered. woodworking equipment during running-in. The use of this method will allow obtaining information about the condition of friction surfaces and the wear rate during transient processes (running-in) in online mode. To justify choice informative AE parameters analyzed the type of AE - signal frames captured during the transition process at characteristic points. It is shown that when evaluating speed wear in transient modes is best use acoustic emission power radiation. After completion transitional process (steady state of operation), the AE signal frame takes the form that much different from transitional regime. Experimental research presented in the form of experimental dependencies thats reflect average value power of AE signals. Along the axis Y postponed relevant calculated value speed works dissipation in tribosystems , unit measurement - J/s. Received dependencies allow determine speed works dissipation in tribosystems woodworking equipment during the transition process by values power signals acoustic emissions, which allowed us to develop a calculation methodology quantities speed wear in woodworking equipment during training in any point transitional process.

Strengthening of tribocoupling parts of transport and agricultural machines with fullerene materials

V.V. Aulin — 2025-03-22

The aim of this work is a comparative study of tribological properties and tribotechnical characteristics of polymer nanocomposites based on polyamide 6, modified with nanosized fillers. The work investigates polyamide 6 as a matrix modified with the following fillers: fulleroid materials (carbon fibers), microsized fillers containing nanoparticles (fullerene carbon black), nanoparticle fillers (fullerene C60).The influence of fulleroid modifiers and carbon fibers on the tribological properties of samples and parts made of polymer nanocomposites based on thermoplastic (polyamide 6) polymer matrices was studied. It was shown that the introduction of fulleroid modifiers allows to significantly reduce the friction coefficient of polymer compositions while increasing their mechanical characteristics. It was found that the use of carbon fibers for modification of polyamide 6 with an increase in mechanical characteristics during operation leads to an increase in the friction coefficient of the conjugated steel sample by more than two times compared to the original polymer matrix.