Antifriction Coatings Research Articles

Investigation of the Properties of Anti-Friction Coatings Deposited with Different Casting Methods.

This article presents the research results of depositing anti-friction coatings (Babbitt) using three different casting methods: static casting, flame soldering, and clad welding. Babbitt alloy coatings deposited with different casting methods are discussed and explained in terms of changes in the coating properties, such as the microstructure, hardness, strength, and chemical composition. The results showed significant differences in the aforementioned properties, depending on the chosen coating deposition method. The results of the tests confirmed the importance of using shielding gas during deposition to ensure the chemical composition of the coating. The analysis revealed that decreases in the amounts of antimony and copper in the Babbitt coating compared with the initial concentrations were influenced by selective evaporation, oxidation, and the coating process parameters associated with different coating methods. To maintain the desired balance of mechanical properties in Babbitt coatings, it is important to control the antimony and copper contents. Clad welding deposition using a non-consumable tungsten electrode and argon shielding gas achieved a chemically stable coating quite close to the initial chemical composition of the Babbitt alloy.

Technologıcal Methods of Increasıng Bearıng Performance

The tribological characteristics of bearing shells manufactured using various technologies have been studied. The results obtained allow us to determine the most technologically advanced method. One of the main requirements for load-bearing shells is the absence of macrostresses in the surface layers of the load-bearing shells, leading to their destruction. The studies were carried out only in near-surface areas. The results obtained show that there are no macrostresses in antifriction coatings obtained by ion-plasma and galvanic methods. An important feature is the high adhesion strength of the antifriction layers to the base. Adhesion tests were carried out on samples cut from liners obtained by the acoustic method. The greatest adhesion strength is observed with ion plasma coating, it is 22 MPa.

Trends for development of processes and machines for strengthening coatings deposition

Results of analysis of "International Conference of Advanced Coatings and Films" literature, which was organized by Institute of advanced coatings and materials in Taizhou university of China were represented. Wear resistance and solid lubricated and antifriction coatings including DLC ta-C coating and combination of a-C:Н sublayer and MoS2 layer were considered. Improve ways of coatings deposition methods, such as microwave PECVD, super HIPIMS, HIPIB ablation plasma were analyzed. Methods of slide friction reduction by laser grain-orientating of steel surface and achieve of super lubrication properties of materials by thin film coatings were shown. A peculiarity of vacuum coaters for strengthening coatings deposition development by Chinese enterprises were analyzed.

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ПРОЧНОСТИ СЦЕПЛЕНИЯ ТВЕРДОГО АНТИФРИКЦИОННОГО ПОКРЫТИЯ С ОСНОВОЙ

The article presents a detailed study of individual samples of MODENGY solid antifriction coatings. The selected solid antifriction coatings are described, the roughness of the applied coatings is analyzed, and measurements of the thickness of the antifriction layer on the surface of steel samples are given. The methodology for determining the quantitative assessment of the adhe-sion strength of a solid antifriction coating based on GOST 32299-2013 was analyzed and a set of experiments using a bursting machine with a built-in electronic force meter IR 5047-50 was con-ducted. As a result, a quantitative assessment of the adhesion strength of solid antifriction coatings with a steel base was obtained. Conclusions are drawn about the adhesion strength of solid antifriction coatings. Recommendations on their use for automotive equipment are given.

Combined Anti-Friction Coatings Based on Nichrome and Copper

Combined Anti-Friction Coatings Based on Nichrome and Copper

ИССЛЕДОВАНИЕ ПРОЦЕССА ПРИРАБОТКИ АНТИФРИКЦИОННЫХ ТВЕРДОСМАЗОЧНЫХ ПОКРЫТИЙ В ПРОЦЕССЕ ЭКСПЛУАТАЦИИ ПОДШИПНИКОВ СКОЛЬЖЕНИЯ

The article presents a brief analysis of the hard-lubricating coatings used. An experimental stand for the study of the lapping process of hard-lubricating antifriction coatings in sliding bearing assemblies is considered. The description of measurements of the roughness values of the lapped surface using the MarSurf PS10 profilometer is given. The obtained dependences of the rotor rotation frequency change on time for various antifriction hard-lubricating coatings are presented. Conclusions and recommendations on the further use of antifriction hard-lubricating coat-ings in friction units are given.

Tribotechnical Properties of Ceramic Antifriction Coatings Based on Iron Oxide and Boron Oxide

Tribotechnical Properties of Ceramic Antifriction Coatings Based on Iron Oxide and Boron Oxide

DEVELOPMENT OF A MATHEMATICAL MODEL FOR ANALYZING THE ECONOMIC EFFECT OF THE MODIFIED DESIGN OF A RADIAL SLIDING BEARING AND ITS PREDICTION

In modern heavy-loaded friction units, various types of antifriction coatings are used on the surface of the bearing profile of the bearing sleeve to ensure high load-bearing capacity and increase the duration of the hydrodynamic regime, and consequently, the economic effect of sliding bearings.
 In the study, the creation and development of mathematical models of a radial sliding bearing with an antifriction polymer coating of the support surface containing a groove is carried out. The key role here is played by the method of analytical forecasting, which determines the mechanism of friction and the conditions for its transition from boundary to liquid.
 The aim of the study is to develop a mathematical model of a radial sliding bearing with a polymer coating of the bearing sleeve bearing surface containing an axial groove to predict the economic effect.
 The objective of the study is to develop new mathematical models and analyze the movement of lubricant in the working gap of a radial sliding bearing, taking into account design features to predict the economic effect.
 The difference from the existing models of tribosystems with antifriction coatings is the presence of a groove, which ensures stable ascent of the shaft on the hydrodynamic wedge and reduces wear during start-up and run-outs, hence increasing the service life of tribosystems.
 Using the lubricant motion equation and the continuity equation, new mathematical models are obtained that take into account the design features of the bearing sleeve surface – polymer coating, groove width, rheological properties of the lubricant used. Based on the results of an experimental study on the AI 5018 friction machine, the economic efficiency of net discounted income was calculated on samples in the form of partial inserts.
 As a result of the research, new mathematical models for engineering calculations have been developed that allow predicting the efficiency, reliability and duration of the hydrodynamic lubrication regime, as well as determining the main tribotechnical parameters. Net discounted income based on the results of theoretical and experimental research is estimated at 0.36 million rubles per year.

High performance tin-based Babbitt coatings deposited by high-pressure cold spraying

Tin-based Babbitt alloys are widely used as sliding bearing materials due to their excellent tribological properties such as good friction reduction, friction resistance and embeddedness. In this study, for the first time, tin-based Babbitt coatings (SnSb11Cu6) were deposited on 40Cr steel substrates by a high-pressure cold spraying system with dual downstream injection as a preliminary investigation of anti-friction coatings for sliding bearings. The effects of process parameters on deposition efficiency, microstructure, microhardness, bond strength and tribological properties of cold sprayed SnSb11Cu6 coatings were systematically investigated. Results showed that with the optimization of process parameters, deposition efficiency tends to increase first and then decrease, and the optimal deposition efficiency achieved is 53 %. The coating prepared at the gas pressure of 1.5 MPa and gas temperature of 450 °C has the highest density, and the best overall mechanical and tribological properties. XRD results showed that no phase change and oxidation occurred for coatings under all cold spraying conditions. The highest microhardness of cold sprayed SnSb11Cu6 coatings is 28.8 HV0.05, higher than that of as-cast alloy (~22.5 HV0.05). The bond strength between SnSb11Cu6 coatings and the steel was significantly increased by using bond coat and is highest as 21 ± 3 MPa. The lowest coefficient of friction and wear rate of the SnSb11Cu6 coatings is 0.23 and 7.99 × 10−5 mm3/N·m, respectively (pair: GCr15 ball, 3 N). The deposition mechanisms and wear mechanisms of cold sprayed SnSb11Cu6 coatings were also analyzed. With the optimization of process parameters, the particle physical state transits from semi-molten to fully-molten, and the bonding mechanism is mainly mechanical interlocking. The wear mechanisms of cold sprayed SnSb11Cu6 coatings are abrasive wear and adhesive wear, and abrasive wear dominates.

РАЗРАБОТКИ ПОДПРОГРАММЫ «МЕТАЛЛУРГИЯ», ВЫПОЛНЕННЫЕ В ИНТЕРЕСАХ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ

The main results of the implementation of the tasks of the subprogram “Metallurgy” of the State Research Program “Mechanics, Metallurgy, Diagnostics in Mechanical Engineering”, 2021–2025, with an applied orientation are presented, which are obtained by the organizations of the National Academy of Sciences of Belarus, the Ministry of Education and the Ministry of Industry of the Republic of Belarus. Their contribution to the solution of practical problems is shown. In the field of metallurgy of iron-carbon alloys, a range of new grades of steels for large gears and large castings of supporting systems of machines are developed. Distinctive features of the developed steels are the possibility to obtain higher hardness values of the hardened layer and teeth of cemented gears compared with counterparts from serial steels. A new sparingly alloyed steel for gearboxes of tractors BELARUS has been developed. The steel is characterized by high hardenability of cemented layer. In the field of metallurgy of non-ferrous metals and alloys, theoretical and technological bases for production of complex configuration castings are developed. Application of these castings improves the dimensional accuracy of products. In the field of hardening of steels and alloys, the technology of coating formation on the working surfaces of metallurgical and foundry equipment parts by mechanical cladding with flexible tool is developed. The coatings provide 1.9 times higher durability of mold parts by compared to the parts without coatings. The technological process of induction cladding on the surfaces of friction nodes parts of wear-resistant antifriction coatings is developed. The service life of bimetallic parts with coatings is 1.25–1.33 times higher than that of serial parts. Physico-chemical principles of creation of aluminomatrix composites were developed on the basis of micro- and ultradispersed oxide powders. This provided a 5-fold increase in tribomechanical properties. In the field of metal forming, the strategy of ring rolling is developed as applied to the nomenclature of rings of the Belarusian enterprises. Technological substantiation is performed for reducing deformations and residual stresses after heat treatment of low-rigid parts such as discs using dynamic stabilization based on alternating cyclic loading.

The Characterization of Soft Antifriction Coating on the Tin Bronze by Electro-spark Alloying

Soft materials such as silver, copper and Babbitt SnSb11Cu6 were deposited on the surface of tin bronze by electro spark alloying (ESA) to form the antifriction coating. The data of the antifriction coating were tested by electronic balance, three-dimensional optical profilometer, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), Vickers microhardness tester and tribometer. The mass gain, roughness, thickness, surface morphology and phase composition, cross-section and element distribution, microhardness and tribological properties of the antifriction coating were analyzed. The results show that the grain size of the antifriction coating is fine and the metallurgical bonding between the coating and the substrate is good. The surface of each substrate is composed of three layers of coating. The optimal parameters of electro spark alloying are as follows: the discharge voltages of Ag, Cu and Babbitt alloy coatings are 60 V, 60 V and 30 V respectively, the energy storage capacitance is 150 μF, 150 μF and 90 μF respectively, and the working efficiency is 3 min/cm2, 3 min/cm2 and 4 min/cm2 respectively. Under the optimized parameters, the average mass transfer efficiency is 54.4 mg/cm2, the average surface roughness is 32.3 μm, and the maximum thickness is about 160 μm. The surface friction coefficient of the soft antifriction coating is 55.6 % of that of the tin bronze substrate. The main wear mechanisms of the soft antifriction coating prepared by electro spark alloying technique are plastic deformation accompanied by slight polishing.

The Effect of Antifriction Coatings on the Drilling Process of Titanium Alloy

The Effect of Antifriction Coatings on the Drilling Process of Titanium Alloy

INCREASING THE WEAR RESISTANCE OF HEAVY LOADED FRICTION UNITS OF ANTI-FRICTION GAS THERMAL COATINGS

Purpose. The purpose of this study is to establish technological conditions and parameters for obtaining materials for improving the performance of machine parts under conditions of heavily loaded friction units due to quasi-tribosystems of gas thermal sprayed anti-friction layers.
 Research methods. Priori data were used in combination with our own scientific developments of the dependences of the influence of the chemical composition of gas thermal sprayed anti-friction layers on the physical and mechanical properties of the surface layer of the material, which is destroyed under tribosystem conditions.
 Results. On the basis of the theoretical and practical scientific research, a set of relevant knowledge has been obtained, which makes it possible to determine the main criteria requirements for obtaining anti-friction layers and graphically describe the characteristics of the alloy and show the correlations of the parameters with each other. The positive role of aluminum as a soft component of anti-friction pseudoalloys, which is well sprayed by thermal metallization at an affordable cost, has been experimentally confirmed. It has been proven that gas thermal coatings in the form of pseudoalloys, consisting of particles with different physical and mechanical properties of materials, can have up to 2–3 times higher wear resistance compared to single-component coatings from materials included in the composition.
 Scientific novelty. Theoretical and practical scientific research with the reproduction of system analysis to increase the resistance to destruction under the conditions of quasi-tribosystems of gas thermal sprayed antifriction layers is given. It is shown that in order to ensure a good running in of the contacting surfaces in the friction zone and particles of hard material with high wear resistance and resistance against sticking with the counterbody, anti-friction pseudoalloys of coatings should contain zones of material particles with lower hardness to comply with the Charpy principle. It has been determined that when spraying composite wires for application as a solid component of anti-friction coatings, it is possible to use particles of alloying elements that form intermetallic compounds or phase components of alloys with a high hardness during melting. A comparative analysis showed that two-component coatings deposited with composite wires are characterized by higher hardness and wear resistance under high contact pressures compared to coatings of the same composition deposited with different types of solid wires.
 Practical value. The obtained results allow, within the framework of technical and technological accuracy, which is necessary in the practical engineering forecasts, to determine the physical and mechanical properties of wear resistant gas thermal sprayed anti-friction layers under conditions of quasi-tribosystems. Thus, in comparison with cast antifriction materials of the same composition, anti-friction layers obtained by thermal metallization have a 1.5–1.8 times higher wear resistance.

Пошук оптимальних параметрів фінішної антифрикційної безабразивної обробки гільз циліндрів автотракторних двигунів

This paper presents the results of research aimed at improving the quality of antifriction coatings obtained by finishing antifriction non-abrasive treatment (FANT). It has been previously established that the formation of an antifriction coating during FANT largely depends on the technological parameters that determine the conditions of contact between the tool and the surface being treated. The study of the peculiarities of surface contact, their regularities, as well as the main parameters of the FANT process, makes it possible to improve the quality of the antifriction coating, and therefore the operational properties of the part. The aim of the presented research is to evaluate the influence of technological factors of the FANT process on the quality of antifriction coatings and to obtain their rational values. The indicators of the quality of the antifriction coating are its continuity, surface roughness and mass transfer of the antifriction material. The optimisation parameters are the main modes of FANT and the geometrical characteristics of the initial surface to be treated. To determine the influence of the selected factors on the indicators characterising the quality of the antifriction coating, a central composite plan matrix was implemented, which allowed us to obtain mathematical models of the influence of factors on the adopted response functions. The processing of the experimental data was carried out using the STATISTICA 12.0 software package. As a result of the multifactorial experiment, statistical models were obtained that allow assessing the impact of the studied factors on the optimisation criteria. The significance of the obtained coefficients was checked using the Student's criterion, and the adequacy of the obtained equations was checked using the Fisher's criterion. A detailed analysis of the Pareto map and tabular results of the experiment allowed to establish the influence of the research factors on the optimisation criteria. The obtained mathematical models made it possible to determine the optimal combination of technological factors that ensure the quality of the coating, as well as to establish the rational values of FANT modes and geometric characteristics of the output surface.

Tribological Properties of WS2 Thin Films Containing Graphite-like Carbon and Ni Interlayers.

The development and production of thin-film coatings having very low friction is an urgent problem of materials science. One of the most promising solutions is the fabrication of special nanocomposites containing transition-metal dichalcogenides and various carbon-based nanophases. This study aims to explore the influence of graphite-like carbon (g-C) and Ni interface layers on the tribological properties of thin WS2 films. Nanocrystalline WS2 films were created by reactive pulsed laser deposition (PLD) in H2S at 500 °C. Between the two WS2 nanolayers, g-C and Ni nanofilms were fabricated by PLD at 700 and 22 °C, respectively. Tribotesting was carried out in a nitrogen-enriched atmosphere by the reciprocal sliding of a steel counterbody under a relatively low load of 1 N. For single-layer WS2 films, the friction coefficient was ~0.04. The application of g-C films did not noticeably improve the tribological properties of WS2-based films. However, the application of thin films of g-C and Ni reduced the friction coefficient to 0.013, thus, approaching superlubricity. The island morphology of the Ni nanofilm ensured WS2 retention and altered the contact area between the counterbody and the film surface. The catalytic properties of nickel facilitated the introduction of S and H atoms into g-C. The sliding of WS2 nanoplates against an amorphous g-C(S, H) nanolayer caused a lower coefficient of friction than the relative sliding of WS2 nanoplates. The detected behavior of the prepared thin films suggests a new strategy of designing antifriction coatings for practical applications and highlights the ample opportunities of laser techniques in the formation of promising thin-film coatings.

Improving the quality of antifriction coatings using plastic deformation

One of the ways to solve the shortage of anti-friction materials based on copper is the creation of anti-friction coatings on the surface of parts made from domestic raw materials. The technology of applying anti-friction coatings by finishing anti-friction non-abrasive treatment on the working surfaces of cast-iron products is considered. The use of deforming broaching to improve the quality of the antifriction coating is proposed. The reserves for their improvement due to the creation of favorable shapes and sizes of microroughnesses in the operations preceding the coating are determined. The study of the contact interaction of the microroughness of the machined surface with the tool was carried out on model samples. The main regularities of the formation of an antifriction coating on a cast-iron surface are established depending on the initial microrelief and processing modes. The effectiveness of the use of deforming broaching when applying an antifriction coating is studied by changing the height parameter of roughness. The performed studies allowed us to propose various schemes of the technological process of applying anti-friction coatings by the friction-mechanical method using deforming broaching, depending on the technical requirements for the product.

Operational Properties of Steel Friction Units with Copper-Alloy Antifriction Coating Formed via Electric Spark Alloying

Operational Properties of Steel Friction Units with Copper-Alloy Antifriction Coating Formed via Electric Spark Alloying

Development of Porous Films Based on Polyanionic Cellulose to Form Functional Coatings

New porous films based on polyanionic cellulose with AlOOH nanoparticles have been developed. The morphology of the films has been studied by electron microscopy: the size of the formed pores is 1000-500 microns; the total surface porosity of the films is 30%. Using infrared microscopy, it was shown that during the formation of porous films, their chemical composition remains unchanged. Differential scanning calorimetry was used to determine the threshold for thermal destruction of porous films: 306 С. The possibility of using the obtained materials as antifriction coatings when filling the pores with solid lubricant MoS2 is considered. It is shown that for a steel sample protected by a porous coating with MoS2, the friction coefficient decreases by 50% compared to the friction coefficient for a steel surface under a load of up to 450 MPa.

Зміна шорсткості поверхні при нанесенні антифрикційних покриттів

The analysis of literary sources made it possible to state that the surface roughness obtained by the finish anti-friction non-abrasive treatment (FANT) is one of the main quality criteria of the anti-friction coating and largely determines the process of running-in during the initial period of operation. The purpose of the presented research is to establish the main patterns of changes in the roughness of the surface layer treated by FANT. Application of anti-friction coatings was carried out according to the method developed by the authors using the original device on a vertical milling machine. Special disc-shaped samples made of gray cast iron SCH20 were used as the tested samples. L63 brass was used as the material of the anti-friction coating. Among the technological factors that changed with the selected FANT scheme, the following were selected: the pressure force of the anti-friction bar and the number of rubbing passes. The roughness of the surface was estimated by the average arithmetic deviation of the Rа profile. The average value obtained as a result of three measurements was taken as the value of the roughness parameter Rа. The obtained values made it possible to establish the main patterns of changes in the roughness parameter depending on the technological parameters of FANT. It is shown that with an increase in the initial surface roughness parameter Rа, the value of the change in the average arithmetic deviation of the profile Ra also increases. High initial values of the arithmetic average deviation of the Ra profile do not allow obtaining a continuous, and therefore high-quality anti-friction coating of FANT. Obtaining a high-quality anti-friction coating with the selected FANT scheme became possible with the following processing modes: pressing force of the anti-friction bar P = 164.6 N; the number of rubbing cycles is N = 6. The results of the studies performed on the application of FANT anti-friction coatings make it possible to predict and control such an important geometric parameter of the surface layer as roughness, which largely determines the quality of the treated surface.

АДГЕЗИОННАЯ ПРОЧНОСТЬ ТВЕРДЫХ АНТИФРИКЦИОННЫХ ПОКРЫТИЙ УЗЛОВ ТРЕНИЯ АВТОМОБИЛЬНОЙ ТЕХНИКИ

The article presents a study of the adhesive strength of solid antifriction coatings of friction units of cars. The results of comparison of domestic and imported solid antifriction coatings are presented. A brief analysis of existing methods for determining the adhesive strength of thin an-tifriction coatings cured under normal conditions is performed. The methodology is described and experiments are carried out using a universal-purpose bursting machine with an electronic force meter IR5047-50. A number of quantitative estimates of the adhesion strength of the antifriction coating to the base have been obtained. Conclusions are made about the adhesion strength of the coating. Recommendations on the application of methods for determining the adhesive strength of thin solid antifriction coatings are given.