The quality and properties of the deposited wear-resistant layers depend on the technological modes of surfacing and the type of filler materials used. The results of studying the structure of filler composite wire for surfacing wear-resistant layers are presented. Wire based on an aluminum alloy (hypereutectic silumin), silicon carbide (SiC) powders, and titanium intermetallic compound (Ti2NbAl) is produced using powder metallurgy. The powders of SiC or Ti2NbAl (taking into account their content in the final material of 5 wt

Functionally organized steel–aluminum laminated compositions are fabricated by friction surfacing. Grade 20 steel is chosen as a substrate material, and ER 1100 and ER 5356 aluminum alloys are chosen as the consumable rotating rod material. The process parameters (axial load, longitudinal displacement velocity, rotation frequency) have been determined to ensure the vertical stability of the consumed rotating rods. The microstructure and phase composition of the diffusive intermetallic layer having formed at the interfaces of the main steel–aluminum composite layers are studied.

The structure and properties of filler rods made of a B83 alloy reinforced with Al–Bi or Ti2NbAl intermetallic particles less than 100 μm in size in an amount of 3 wt

Composite material specimens are fabricated by reaction casting by mixing titanium particles to form Al3Ti intermetallic phases. Dry sliding friction tests are carried out according to the scheme of end loading of a fixed sleeve (grade 45 steel) on a rotating disk (specimen) at sliding speeds of 0.25–0.75 m/s and loads of 0.5–3.5 MPa. Wear intensity maps, which determine friction regimes during a test, are constructed. The boundaries and conditions for changing the friction regimes are shown.

The technology of obtaining surfacing materials for the subsequent formation of functional composite layers on steel bases of friction units is presented. Composite surfacing rods were obtained by extrusion of a powder compact from granules of matrix antifriction alloy AO20–1 and ceramic powders of micron (SiC) and submicron (TiC) sizes. The modes of obtaining matrix alloy granules, composite mixtures and extrusion are given.

The paper deals with the effect of Ti2NbAl intermetallic additives on the friction processes of hot-extruded B83 babbitt specimens. Optical and electron microscopy and energy-dispersive analysis were used. The structure, friction surface, and wear products were studied. Tribological tests were performed under dry sliding friction conditions using a universal testing machine according to an axial loading scheme of a steel sleeve to a disk made of the test material. The values of temperature near the friction zone were recorded during tests. The applications of the material depend on the wear regimes and mechanisms occurring in the tribocontact. Changes in wear regimes and mechanisms were assessed in terms of differences in the behavior of the friction coefficient and temperature, differences in the condition of friction surfaces and wear rates, and products of wear. The results suggest that hot pressing of powder containing the alloy B83 and discrete particles of the high-strength intermetallic phase Ti2NbAl is a promising method for producing composite materials with better tribological properties than the babbitt alloy. The introduction of reinforcing high-modulus particles of intermetallic compounds changed the structure of the material and affected the friction processes in the babbitt alloy, delaying the moment when wear regimes shifted into the zone of more severe friction conditions. A substantial reduction in the wear rate of the produced composite materials compared to the initial alloy makes it possible to predict the increase in the service life of tribounits. These data can help determine and recommend the regimes for increasing the service life of tribounits based on B83 alloy as volumetric liners and plain bearings (or sliding bearings), as well as produce new functionally structured layer compositions having enhanced tribological properties, which are based on structural steels and surface coatings using not only B83 babbitt alloy but also its composite materials.

A mathematical model for studying temperature and time conditions of the process of friction surfacing in the manufacture of functionally organized steel-aluminum compositions has been developed and validated. Bars made of pure aluminum grade ER1100 were used as the consumable rod material during friction surfacing. The substrate in the form of a rectangular plate was made of high-quality steel 20. The geometric model of the object when modeling the process of friction surfacing in the ANSYS 2021R2 software package was specified in the form of a rod and a substrate. The initial data for calculating temperature-time conditions of the friction surfacing process are: geometric parameters of the simulation object; characteristics of thermal loads of the heating source which depend on the technological parameters of the surfacing mode (the speed of axial rotation of the rod, axial pressure, boundary conditions of the simulation object for the temperature problem), and auxiliary parameters that determine the order of calculations. The thermal power arising at the point of physical contact between the rotating consumable rod and the substrate was considered a parameter of the source thermal load. The calculation of heat propagation for the friction surfacing process was carried out according to a scheme with a normally circular source located on the substrate surface. The calculation scheme directly reflects the main feature of the friction surfacing process: the introduction of heat due to friction between the rotating consumable rod and the substrate. It is shown that taking into account the boundary conditions and geometric features of the 3D model provide a satisfactory convergence of developed mathematical model and ensure the uncertainty of no more than 5 % in determining the heating temperature of the substrate when forming functional aluminum coatings, as well as composite materials on their base when surfacing them on the surface of steel substrates.

The effect of additives of Ti 2 NbAl intermetallic compound on the friction of B83 babbitt samples obtained by hot pressing was studied using optical, electron microscopy and EDS analysis. The structure, friction surface and wear products were studied. Tribological tests were carried out on a universal test system under conditions of dry sliding friction according to the scheme of axial loading: a steel bush against a disk of the material under study. The temperature values near the friction zone were recorded. The limits of application of the material depend on the mode and mechanism of wear occurring in the tribocontact. Changes in the mode and mechanism of wear were assessed by differences in the behavior of the friction coefficient, temperature, difference in the state of friction surfaces, wear intensity and wear products. The results obtained indicate the prospects of using the method of hot pressing of powder from the B83 alloy and discrete particles of the high-strength Ti 2 NbAl intermetallic phase to get composite materials with improved tribological properties compared to a babbitt alloy. The introduction of reinforcing high-modulus particles of intermetallic compounds changed the structure of the material and affected the friction processes in babbitt, pushing aside the onset of change in the mode of wear towards more severe friction conditions. A significant decrease in the wear intensity of babbitt-based composite materials compared to the original alloy makes it possible to predict an increase in the service life of tribo-units. The data obtained enable us to determine and recommend modes that improve the performance of tribo-nodes in the manufacture of both volumetric inserts and plain bearings made of B83 alloy and, moreover, to create new functionally organized layered compositions with enhanced tribotechnical properties with a base of structural steels and working surface layers not only using B83 babbitt, but also of composite materials based on B83 babbitt.

A mathematical model for analysis of temperature–time conditions of arc surfacing upon fabrication of steel-aluminum compositions has been developed and verified. In the course of simulation, the database of SVARKA software has been supplemented with thermophysical properties (thermal conductivity and thermal capacity at constant pressure and volume) of the considered materials as a function of heating temperature. The geometric model of the object during simulation of arc surfacing has been preset as a single body, which can consist of various materials, for instance, in the case of formation of functional coatings based on nonferrous metals on steel substates. The parameters of the heat loads of the heating source are as follows: motion speed of motion, power, distribution along and across seam, as well as existence and grade of surfacing material. The heat propagation for argon arc surfacing using a non-consumable electrode has been calculated according to the design with a normal circular source located on the surface of a flat layer and exposed to limiting action of the sheet bottom plane. The selected calculation design reflects all the main features of argon arc surfacing, including the welding arc heat input to a massive body from its surface, low pressure of welding arc, and insignificant penetration of active spot into liquid metal. It has been demonstrated that, owing to accounting for thermophysical properties of the Fe–Al intermetallic layer located in diffusion zone, the mathematical model with uncertainty not exceeding 8

Composite materials based on aluminum, reinforced withparticles of titanium carbide and intermetallic compounds of titanium aluminide, are made by casting technology. Investigations of the structure, mechanical and tribotechnical characteristics of the manufactured composite materials have been carried out. It is shown that the reinforcement of an aluminum matrix with TiC particles, or intermetallic phases of Al3Ti, formed by introducing reactive titanium powders into the melt, is an effective way to increase the tribotechnical characteristics. It has been established that the reinforcement of the aluminum matrix with TiC particles has a greater effect on the reduction of the friction coefficient and the wear rate, in comparison with the reinforcement with intermetallic phases Al3Ti, despite the higher volume fraction of the latter. It has been determined that the greatest wear resistance is provided by hybrid reinforcing of an aluminum matrix with TiC particles and intermetallic phases. The additional introduction of stronger TiC particles leads to a decrease in the load on the Al3Ti intermetallics, thereby preventing their destruction under the action of high external loads. In addition, the presence of a larger number of reinforcing phases in hybrid composite materials than in other composite materials samples provides not only a decrease in the load on each reinforcing particle separately, but also a decrease in the fraction of the matrix in the friction surface, thereby expanding the range of triboloading.

The structure and properties of aluminum-matrix composite coatings for tribotechnical purposes, formed on steel substrates, have been investigated. Preliminarily, to limit the interaction between the materials of the substrate and the matrix of the composite material, i.e. iron and aluminum, an intermediate layer of pure aluminum was applied to the substrate surface by the explosion welding process. It is shown that the deposited composite coatings of Al-12Si + 10 wt.% SiC (40) are characterized by a uniform reinforcements distribution, and their adhesion strength values reach 66 MPa. According to the results of friction and wear tests under dry sliding friction conditions, it was determined that the manufactured samples have a 50% higher wear resistance compared to industrial bimetallic materials made of steel 20 with a B83 babbit coating, and their use in friction units will significantly expand the range of triboloading of the promising constructions.

In this work, study of wear modes of antifriction layers of B83 babbitt during tribological tests was carried out. The assumed conditions for changing wear modes were determined during testing with a continuous increase in load by analyzing data of changes in the coefficient of friction and temperature near the contact zone. The data obtained made it possible to conduct experiments for a deeper study of the processes occurring in the friction zone. The results of friction experiments and studies by electron microscopy confirmed the correctness of the assumption about the conditions for change of wear modes. Changes in wear modes and wear mechanisms were judged by the behavior of the friction coefficient, the difference in friction surfaces, wear products, and wear intensity. The results obtained will make it possible to determine and recommend the modes of “wear-free” operation of the babbitt alloy.

There was analyzed the distribution uniformity of reinforcing particles Ti2NbAl in composite materials (CM) based on aluminum alloy AO20-1, made by mechanical mixing. Samples with different structure dispersion were obtained by crystallization of a composite melt in molds made of materials with different thermal conductivity. There were used methods of digitizing the structure microphoto and mathematical statistics to estimation structural heterogeneity. Based on the results of processing the photographic images, there were constructed histograms of the frequencies of the distribution of intermetallic particles in the matrix. It is revealed that matrix structure refinement has positive effect on uniformity of the distribution. A significant decrease in the coefficient of variation for specimens with a finer structure also indicates a more uniform distribution of the reinforcing phase in this specimens. There was compared a wear resistance of the material and the uniformity of distribution of the Ti2NbAl powder in the matrix. A wear rate of composite materials was determined by testing on CETR UMT Multi-Specimen Test System under dry sliding friction conditions with sequential stepwise axial loading to values of 0.5, 1, 1.5, 2, 2.5, 3 MPa, at constant sliding speed of 0.5 m/s. The test time for each axial load was 2000 s, the friction path was 6000 m. It was observed a significant reduction in weight loss during friction for all CM samples as compared to the matrix alloy. The wear rate of CM specimens with a better distribution of the reinforcing component is reduced by more than 2.7 times as compared to specimens from the AO20-1 alloy, and with a less uniform distribution by 2.2 times

Interaction at the interface during the production of functional steel-aluminum compositions by arc processes has been investigated. Regularities and mechanisms of the diffusion zone formation have been proposed upon contact of a melt based on aluminum, alloyed with 11-13 wt% Si, with the steel substrate or Al-Fe system intermetallic compounds. It was found that the presence of Si in the composition of filler material leads to diffusion mobility of Al and Fe decreasing due to the replacement of Al, as well as the occupation of structural vacancies in double FexAly intermetallics and ternary intermetallic phases with different stoichiometric composition FexAlySiz formation. It was determined that during the arc cladding process using as substrate the steel with intermediate zinc coating, a diffusion zone with an average thickness of 7 μm is formed, while in the presence of an intermediate coating from aluminum deposited by the “cold metal transfer” process, its average thickness is 18 μm.

Composite coatings of the SnSbCu–Ti2NbAl system are formed on steel substrates by arc surfacing using a tungsten electrode in an inert gas. The welding materials were composite rods based on a B83 babbit alloy containing 3 wt % Ti2NbAl particles with sizes of at most 100 μm manufactured by extrusion. The structure and the mechanical and tribotechnical properties of the deposited coatings are studied. The cross-sectional areas of intermetallic SnSb inclusions are found to be 100–500 μm2 in the deposited composite coating and from 1000 to 10 000 μm2 in the coating prepared by cast technology from an Sn–Sb–Cu matrix alloy. The geometric shape of the intermetallic SnSb inclusions in the deposited coating structure is found to be rounded, while, in an as-cast sample, it is the equilateral acute-angled. The hardness of the composite coating is higher by 50% and its volume wear intensity is lower by 21% as compared to those for the as-cast matrix alloy; in addition, the composite coatings have good adhesion with the steel substrate, continuity, and defect-free of the fusion line.

The structure and tribological behavior of composite materials (CM) based on the AO20-1 alloy produced by casting method by mixing particles of the Ti 2 NbAl intermetallic compound into the melt were studied. Tribological tests of the samples were carried out under conditions of dry sliding friction according to the axial loading scheme of a rotating disk sample using a fixed sleeve made of steel 45X ( HRC > 63) as a counterface. It has been established that, as a result of a decrease in Al grain size during the rapid crystallization of the matrix alloy and the introduction of a discrete powder of an intermetallic compound into the alloy, the friction coefficient of the CM decreases by half. The wear resistance of CM increases by 2.5 times, which is associated with the influence of particles of solid intermetallic metal, limiting plastic deformation and entrainment of the matrix material.

Сomposite material samples were obtained by the method of reaction casting by mixing titanium particles to obtain intermetallic phases Al3Ti. Dry sliding wear tests were carried out using a fixed sleeve (steel 45) against a rotating disk (sample) at sliding speeds from 0.25 to 0.75 m/s and loads from 0.5 to 3.5 MPa.There were constructed maps of wear rate, which determine the friction modes during testing. There were shown boundaries and conditions of changing wear modes.

The use of chromium carbides in flux-cored wire for applying abrasion-resistant coatings is considered. It is found that such use of chromium carbides does not result in reinforcement of the resulting coatings by intact carbide particles. However, the replacement of ferrochrome by chromium carbides changes the structure of the wire and coatings, with increase in the hardness.

Tribological properties of a composite material with intermetallic reinforcing based on an antifriction alloy of Al-Sn-Cu system are studied.The samples were obtained by the method of reaction casting mixing micron-sized titanium particles into the melt of the matrix alloy.The formation of intermetallic phases led to an increase in the hardness and a decrease in the wear rate of the sample of composite material.Dry sliding wear tests were carried out using a fixed sleeve (counterbody made of steel 45) against a rotating disk (composite material) at sliding velocities of 0.25, 0.5, 0.75 m / s and loads 0.5, 1, 1.5, 2, 2.5, 3 MPa.Wear rate of the samples and friction coefficient for the entire set of tribo-loading parameters were determined.A general increase in the wear intensity with increasing test load was shown.There was no general tendency of the change in the wear rate with the increasing test velocity.The change in the friction coefficient during the test made it possible to determine the wear modes.The temperature change in the friction process was an additional parameter for describing the wear modes.An increase in load and velocity led to an increase in the friction temperature, in addition, the rate of temperature change was significantly influenced by the test time for equal friction paths.Maps of the wear rate which determine the wear modes during testing are constructed.The bounds and conditions of changes between the four modes of wear, soft, mild, severe and critical, are shown.Optimal loading parameters of the friction process corresponding to the sliding velocity 0.5 m / s and load 1.5 MPa are determined.The constructed wear maps made it possible to determine the friction regimes under which the exploitation of the composite material studied will be carried out in the region between soft and mild wear regimes.