Multicomponent stainless steel and copper (SS/Cu) alloys were produced using dual wire-feed electron beam additive manufacturing added with 50 vol. % stainless steel. Tribotechnical pin-on-disk tests under conditions of dry friction were conducted at a sliding speed of 5 m/s and a contact stress of 0.13 MPa (1.17 N) with and without passing electric current via specimens oriented with the grown layers parallel and perpendicular to the worn surfaces. Upward dependences of wear and downward dependences of friction coefficient on electric current power were obtained. It was found that sliding at low electrical power up to 40 W is similar to the unlubricated sliding with-out passing the current ion, characterized by adhesive wear and the formation of a material transfer layer. Passing electric current at a power above 40 W led to a transition from an adhesive wear mechanism with triboxidation elements to an adhesive with intensive transfer of material to form smooth transport layers containing oxides (spinels). The obtained relationships did not reveal differences related to the orientation of the grown layers of the sample relative to the friction surface. It was concluded that spinel formation is associated with the mechanism of tribochemical adaptation of the SS–Cu system to load conditions. The results of the study represent an important step in the development of tribocomposites based on heterogeneous materials for power equipment (bearings of heavy-duty electrical machines) and electronics (heat-removing elements with a wear-resistant coating).

One of the main tasks that are solved in the process of developing specialized contact fatigue test rigs is the choice of a reliable method for identifying damage on the specimen surface. The paper presents the results of testing the method of spectral analysis of vibration signals and the envelope of their high-frequency components on a test rig for rolling bodies of ball bearings. For determine and select reliable vibration diagnostic parameters corresponding to various degrees of development of contact fatigue failure, calibration samples with artificially inflicted damage of various sizes were tested. In the frequency range 10—10,000 Hz range the most damage-sensitive vibration parameters were identified and their threshold levels were established relative to damage size and the used placement of transducer. Criteria for semi-automatic test termination upon reaching the critical stage of specimen failure were defined. The validity of the methodology for surface condition diagnostics and monitoring during the operation of a pilot (non-standardized) test rig has been experimentally substantiated. Results from a series of tests confirm the effectiveness of the selected and implemented approaches. The findings have been integrated into a vibration monitoring system and used to develop methods for research, quality control, comparative, and other types of laboratory contact fatigue testing of rolling bearing elements.

The structure, phase composition and tribotechnical properties of Ni–2.8B and Ni–8.8P coatings were studied during friction in a biodegradable lubricant based on rapeseed oil. It is shown that in the initial state, the deposited Ni–B and Ni–P coatings have the structure of an interstitial-substituted solid solution of boron/phosphorus in a nickel matrix phase containing a large number of crystal lattice defects. It was found that annealing of Ni–2.8B and Ni–8.8P coatings at 280 °C and 420 °C, respectively, leads to the decomposition of the supersaturated solid solution of boron and phosphorus atoms in the matrix nickel phase with the release of strengthening intermetallic compounds Ni₃B and Ni₃P. The release of strengthening phases during annealing of Ni–2.8B and Ni–8.8P coatings is accompanied by an increase in their microhardness to 1020 HV 0.05 and 870 HV 0.05, respectively. It is shown that annealed nickel-boron and nickel-phosphorus coatings are characterized by high wear resistance and a low coefficient of friction during frictional interaction in a biodegradable lubricant environment. The highest tribotechnical properties are achieved when using an annealed Ni–2.8B coating. It has been established that during the friction process, an increase in microhardness and physical broadening of the diffraction lines of the matrix solid solution of nickel coatings is recorded, which indicates the generation of dislocations in their surface layers. The intensity of linear wear of nickel coatings corresponds to class 9 of wear resistance of friction pair materials. It was established that the modifying Au–Co film applied to the surface of nickel coatings does not have a significant effect on the wear resistance of the coatings under high specific loads of tribotechnical tests.

Currently, metalworking enterprises are growing requirements for the quality of products, as well as for increasing the productivity of finishing operations. To a large extent, the final result is influenced by the quality of the grinding tool. The purpose of the work is to study the effect of the size and geometry of abrasive grains on the increase in the strength of the abrasive tool and the efficiency of the grinding process.

At STC “VNIIASH” VPI (branch) of Volgograd State Technical University, a method of vibrodynamic classification of abrasive materials has been developed, a software module has been created to determine the required particle sizes of abrasive materials. Thus, within the framework of the cyberphysical system for designing abrasive structures, high-performance selection of abrasive grains in size and shape has become possible. It is also possible to formulate abrasive mixtures to produce a high performance abrasive tool. In the course of the work, comparative tests of samples of abrasive in-tools for strength and experimental testing of the efficiency and quality of grinding with experimental tools were carried out. It has been found that experimental grinding wheels have higher grinding efficiency and quality. The best results were obtained by grinding with an experimental wheel made of a mixture of grains of different grain size, the superior results of a serial wheel for steel ShKh15 by about 1.4 times, and for steel R18 — by 1.2 times.

Such an abrasive tool has increased mechanical strength, the ability to self-sharpen and regenerate the working surface, forming additional surface pores, and provides high performance of abrasive processing.

The aim of the work is to evaluate the influence of various antifriction additives on the tribological characteristics of spherical plain bearings made of glass-epoxy composite material under conditions close to operational ones. Tribological tests were conducted on an tribometer IMASH-JOINT plain bearing machine using a shaft-sleeve configuration with reciprocating rotation at a rotation angle of 52° and a frequency of up to 0.5 Hz in air and water environments at specific pressures of 2.7—8.3 MPa. Test results showed that adding PTFE in the form of ground Fluoroplast-4 powder to the glass composite (30 g of the mixture) has a beneficial effect on the friction coefficient of the spherical plain bearing when operating in air in a load range of 2.7—8.3 MPa and an oscillation frequency of 0.25 Hz. Using Fluoroplast-4 powder additive according to GOST 10007–72 leads to a decrease in the friction coefficient and increased wear resistance during longterm tests in water. The friction coefficient of this material when tested in water at p = 8.3 MPa does not exceed 0.24 after 4 hours of operation. The minimum wear rate of the hinge joint in water was observed for the sample of Fluoroplast-4 powder additive according to GOST 10007–72 and amounted to 3.34×10^–6 mm per cycle. The study revealed the effect of PTFE and graphite additives in the studied volumes on the friction coefficient kinetics of a plain bearing during long-term testing. The obtained results allow us to recommend an optimal formulation for the manufacture of bearings made of glass-epoxy composite material for use in hydraulic turbine units.

The aim of this work is an experimental study of the effect of the abrasive tool bond material (bakelite, ceramic and vulcanite) on the quality (roughness and burns) and productivity (specific productivity, cutting forces, vibration resistance) of the grinding process of austenitic stainless steel 12Kh18N10T in order to substantiate the choice of the optimal bond type.

The paper presents experimental results of a study of the effect of the material of the abrasive tool bundle (AT) on the quality and productivity of the grinding process of austenitic stainless-steel grade 12X18H10T. The paper compares silicon carbide circles with three types of bundles: bakelite, ceramic and vulcanite.

According to the research results, it has been established that the bakelite bundle is the most preferred. The circles with this bundle demonstrate high specific productivity, stability of cutting forces, low tendency to vibrations and burns. The circles with the ceramic bundle showed increased wear and a tendency to cauterization after numerous cutting cycles, and the tool with the vulcanite bundle led to cauterization from the first passages.

Thus, it is advisable to use AT with a bakelite binder when grinding austenitic stainless steel, which will minimize burn-in by 80 %.

The objective of this study is to investigate the effect of heat treatment on the tribological properties of L63 brass with a structure formed after equal-channel angular pressing (ECAP).

The object of this study is L63 brass in various structural states and with distinct mechanical properties. The structure and properties were formed by severe plastic deformation using ECAP and low-temperature annealing. Transmission electron microscopy was used to examine the structure of the samples. Mechanical properties were evaluated under tension, and the hardness of the samples was determined. Sliding friction was measured using a ball-on-disk tribometer without the use of lubricants. The friction coefficient, vibration amplitude, and acoustic emission in the tribocontact were recorded. Metallography was used to study the state of the material's near-surface layer after friction. The friction surface and wear of the brass were studied using confocal laser scanning microscopy.

It was found that ECAP at room temperature increases the strength of L63 brass by 2.1—6 times and its nanohardness by 53—78 % relative to hot-rolled bar. Subsequent annealing reduces these values. The friction coefficient in the steel—brass pair after ECAP decreases by 7—11 %, and after annealing, it increases by 12—28 %, but remains 3—13 % lower than that of the original coarse-grained material. Wear resistance after 1—2 ECAP passes increases by ~ 40—47.5 %, while after 3 passes, it decreases by ~ 10 %. Annealing at 200 °C produces the greatest effect (wear resistance increases by 74—86 %), while annealing at 300 °C increases wear resistance by 36—68 % compared to the initial level. Vibrometry revealed a correlation between vibration acceleration amplitude, wear, and the friction coefficient, which is associated with wear particle formation and adhesive adhesion. The dominant wear mechanisms were found to be adhesive adhesion and fatigue failure affecting the mechanically mixed material layer.

This article provides an overview of studies on the effect of fine solid particles on the tribotechnical properties of greases. Some antifriction (coefficient of friction) and anti-wear properties (diameter of the wear spot) of greases with the addition of particles of various sizes (microparticles and nanoparticles) and of various natures (molybdenum disulfide, nanocarbon additives, copper-based additives, superhard materials) were analyzed. Statistical data on publication activity for each type of additive on the general topic “lubrication” and on the subcategory “greases” were presented. The search depth was 20 years. Despite the differences in the nature of the reviewed materials, general trends in their development as additives for greases have been identified. In all cases, it was noted that nanoparticles were more effective than microparticles. The values of the optimal particle size and additive concentration have been identified for some materials. The main promising areas of research are the study of nanocomposites and the use of several nanoadditives to achieve a synergistic effect. The complexity and multifactorial nature of processes in the friction zone is noted, which makes it difficult to more accurately and in detail assess the effect of additives on the tribotechnical properties of lubricants. The use of artificial intelligence for processing and analyzing large amounts of tribological data is proposed as a potential solution to this problem.

The aim of this work is to synthesize diamond-like carbon (DLC) films using physical vapor deposition (PVD), determine their sp²/sp³ phase composition, and investigate the tribological properties of a multilayer system consisting of DLC layers and titanium/titanium nitride adhesion sublayers on a steel 45 substrate. Two DLC films were produced using the BRV600 magnetron sputtering system, one in a hydrogen atmosphere and the other without hydrogen addition to the process chamber. XPS analysis of these films revealed that the sp²/sp³ phase ratio was approximately 0.2 for the film synthesized with hydrogen and 0.02 for the one without it. The tribological behavior of these DLC films depended on the sp²/sp³ ratio hybridized bonds and the gas atmosphere during synthesis. The interaction between the test ball and initial surface of a film formed in a hydrogen free atmosphere started with a friction coefficient of 0.45, while it started at 0.35 for a film formed under hydrogen conditions. After 1,000 cycles, graphitization of the surface occurred in both wear tracks accompanied by transformation of sp³ into sp². This led to an increase in the sp²/sp³ phase ratio within the wear tracks, reaching a value of approximately 2 for both films after 6,000 cycles. At this sp²/sp³ ratio, the friction coefficient dropped to approximately 0.1.

The purpose of the work is to obtain patterns of changes in the thickness of the oil film in cylindrical gears depending on the dynamic viscosity of the oil; the total rolling speed, the sliding speed of the teeth, and the contact pressure in the gears during friction.

Cylindrical gears of a closed type operating in transmission oil at contact stresses not exceeding 2500 MPa and at an oil temperature of not more than 150 °C. were studied.

A method for calculating the thickness of the oil film is proposed, taking into account the sliding speed between the contacting surfaces of gears; as well as the sequence of calculating the total thickness of the oil film, taking into account contact deformations, the value of which depends on changes in the hydrodynamic properties of the oil during friction. The results of a study of the factors influencing the thickness of the oil film between the friction surfaces of the teeth at a total rolling speed of 6.12 m/s have been obtained. The sliding speed range is 1.0—3.0 m/s, the contact pressure is 186.9—457.9 MPa, and the dynamic viscosity of transmission oil is 17.44—24.24 MPa/s. The calculated values of the oil film thickness vary widely from 0.97×10^–6 m to 2.06×10^–6 m, patterns of changes in the thickness of the oil film are obtained from: dynamic oil viscosity at a constant value of the total rolling speed and contact pressure; rolling speeds in the presence of slippage between the gears.