Journal of Friction and Wear最新文献

With the continuous improvement of transportation infrastructure construction, it not only improves the road traffic conditions, but also promotes the development of the national economy. After many highways are put into use, it is found that although the quality and performance meet the design requirements, the anti-skid performance of the pavement gradually decreases with the wear of vehicles. Therefore, it is considered to add a curing agent in the base material to improve the anti-skid and wear resistance of the pavement. The viscosity of concrete strength is reduced and the internal friction angle is also reduced due to the continuous dry-wet cycle. The above reaction changes prove that the quality of concrete strength can be predicted according to the decline rate of elastic modulus, and the quality and acceptance of subgrade engineering can be technically demonstrated. In this paper, based on the influence of solidified polymer on the quality and performance of pavement base material, according to the physical structure and chemical reaction changes of different polymers on pavement base material, we use different additives such as lime to form adhesion between concrete materials. We hope to improve the wear resistance and permeability of polymer on pavement base material. According to the changing trend of the strength of the pavement base material caused by the different proportions of the stabilizer in the conjugate test, we designed the soil-lime solidification stabilizer. We further optimized the selected materials and the proportion scheme to meet the requirements of the strength, permeability, durability, and other indicators of different roadbeds, which is to improve the wear resistance of the roadbed and form the corresponding material proportion model. Through experimental analysis, from the test parameters and microscopic observation, we prove that the curing agent has a setting effect on the pore structure of the concrete bonding surface, which provides a scientific basis for solving the requirements of complex pavement in highway construction.

A method and a device for testing materials for resistance to gas-abrasive wear at normal temperatures and temperatures elevated to 1000°C is developed. The test results provide a substantiated choice of surfacing materials for restoring working surfaces of parts of exhaust fans, industrial fans, top-charging gear, gas turbine units, and other equipment. The dependences of the wear of some surfacing alloys on the test temperature, gas-abrasive flow velocity, and the angle of its attack on the sample surface is determined. It is shown that under conditions of high-temperature gas-abrasive wear at small attack angles and increased speed of abrasive particles, it is advisable to use eutectic alloys with a reduced content of expensive carbide-forming elements and carbon, and at high attack angles and low-speed abrasive, heat-resistant and refractory austenitic steels. It is found that the foreign deposited C6.0Cr23Nb7Mo7W2Si2VT alloy, characterized by the highest alloying level and volume fraction of strengthening phases, has the highest resistance to gas-abrasive wear at normal temperatures among those tested. When the test temperature increases to 600°C, its wear resistance decreases by 2.5 times, yielding to the indicator of the experimental C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy. The processes of destruction of thin surface layers of alloys are studied using the electron-ion microscopy method, which makes it possible to evaluate the influence of their structural and phase composition on the high-temperature wear mechanism. The study of the wear pattern of the C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy showed that under the impact action of the abrasive, cracks are formed in lamellar carbides Me₃C₂ and Me₇C₃, but the high plasticity of nickel-alloyed austenite reduces the likelihood of breakdown of the resulting fragments. At the same time, small carbides (Ti,Nb,Mo)_xC_y and Mo₂C of a compact form restrain the plastic deformation of the austenite-carbide eutectic without destruction.

Tribological properties of VT22 and Ti-5553 titanium alloys are improved due to the chemical-thermal treatment of their surfaces and the application of a wear-resistant titanium nitride coating. The tribological properties were compared for samples without additional surface treatment, with surface modification by nitriding, with the titanium nitride coating, as well as with a two-stage treatment of sample surfaces, including primary nitriding of the surface followed by the application of a titanium nitride coating on it. It was found that low wear resistance is observed in titanium samples without coatings, while the wear resistance of samples with a nitrided surface layer increases for both types of tested alloys. Minimal wear occurs for the samples with two-stage formation of a titanium nitride coating while on samples without an intermediate nitrided sublayer, when tested with a ceramic ball, delamination of the coating is observed; the formation of the sublayer prevents this type of destruction.

The effect of silica addition (in the concentration range of ({{C}_{{{text{Si}}{{{text{O}}}_{2}}}}}) from 0 to 6 mol %) to alumina toughened zirconia ceramics (stabilized in the tetragonal phase with calcium oxide) on its friction coefficient and wear intensity is investigated. It is found that with an increase in the SiO₂ concentration, both characteristics undergo non-monotonic changes with a general tendency to increase. A comparative analysis of the dependences of mechanical properties (microhardness, fracture toughness and brittleness index), transformability of the tetragonal phase t-ZrO₂, and wear intensity on the SiO₂ content in the composite ceramics is performed. It is shown that the non-monotonic nature of the dependence of the wear intensity on the SiO₂ concentration is due to the competitive effect of changes in microhardness, fracture toughness, and transformability of t-ZrO₂ caused by the introduction of silicon dioxide into the ceramics. A proposal is made on the feasibility of producing silicon-containing ceramics (with increased fracture toughness and compressive strength, as well as a margin of ductility at room temperatures) with a surface layer that does not contain SiO₂, retaining the preferred values of microhardness, friction coefficient, and wear intensity.

This work discusses the synergetic principles of fatigue failure, which allow for the identification of fundamental mechanical characteristics of materials and the assessment of damage kinetics during metal failure through critical parameters that control bifurcation points. Fatigue failure herewith is considered as a kinetic process dependent on the order of energy input from cyclic loading. Based on the principles of physical mesomechanics and synergetics, it is shown that the mechanical characteristics of cyclically loaded tribocontacts are important material parameters that determine the level of deformation energy introduced in each loading cycle at every scale. It has been identified that in tribocontacts, for practical purposes, it is necessary to ensure that the stress between the coating and the substrate corresponds to the ultimate elasticity of the materials, according to Griffith’s criterion, while for viscous materials, a different value of critical stress is taken into account: Irwin–Orawan modification. Criteria for transitional contact modes are presented, considering that the coating should undergo changes in full accordance with the substrate when the system is deformed under cyclic loading. The results of the research on assessing the mechanical characteristics of materials in the “coating–substrate” system can be used as diagnostic indicators when analyzing the development of damage in tribocontacts operating under conditions of cyclic fatigue loading.

When developing materials for moving joints and friction units operating in outer space, the wear resistance of friction pairs with friction coefficients from 0.05 to 0.1 is of particular importance. The values of the friction coefficients determine the heating of the interfaces and the power of the drives. Wear resistance regulates the service life of friction units. The choice of diamond-like coatings as one of the elements of the friction pair determines the high wear resistance of the interface when working with solid lubricant coatings due to their high chemical inertness and the absence of substance transfer from the solid lubricating coating to the diamond-like coating. This paper presents the results of testing diamond-like coatings during friction on EONIT-3 solid lubricant coating and tests in air and vacuum up to 10^–6 mm Hg according to the shaft-bushing scheme in the temperature range from –50 to +50°C. A diamond-like single-crystalline coating 20 μm thick was applied to a shaft made of ShKh-15 hardened steel; EONIT-3 coating with a thickness of 15 μm is applied to a steel bushing. Tests were carried out under a normal load of 100 N; shaft rotation speed—200 rpm; sliding speed—0.12 m/s; and test duration—1 h. The friction coefficients and wear of the solid lubricant coating were measured. No wear of the diamond-like coatings was detected. The wear of the solid lubricant coating ranged from 1.065 × 10^–8 mm³/m to 3.195 × 10^–8 mm³/m at temperatures from –50 to +50°C in air and in vacuum of 10^–6 mm Hg.

The results of research on the modernized SKI LX bench, which provides addition to the model fluid of various kinds of abrasive particles, the nature and properties of which can correspond to real operating conditions, are presented. In developing the program and methodology of these studies, we used the after exploitation analysis of high-speed pumping units carried out at the fields of various companies in the Russian Federation. The features of wear and the mechanisms of destruction of the working stages of the 92ELNC85-2250-e2OE-10ETS high-speed pump series were investigated. On a real design of a high-speed pump the possibility to determine the wear rate of tribo-contraction elements by the method of its weight determination with a forecast for the resource and to reveal the ways of its increase in a wide range of the number of suspended abrasive particles in the model fluid, and in particular, in water is shown. The results in this work are the basis for the development of scientifically based methods for studying the wear resistance of bearing assemblies of high-speed centrifugal pumps in conditions of a wide variety of reservoir fluids and suspended particles contained in them.

Research is carried out on the wear resistance and friction coefficients of a friction composition made from PC30, Al₂O₃, SiO₂, TiO₂, and Cr₂O powders and an additive containing carbon fiber in combination with GE-1 graphite, using the SFP-012A phenolic powder binder material. The study of tribotechnical properties is carried out on an IM-58 inertial stand. Using a stereoscopic microscope and a scanning electron microscope with a micro-X-ray spectral attachment, the morphology of the friction surfaces of experimental samples is analyzed, and information about the elements forming the friction surface is obtained. It is established that promising additives for the friction composition are 5–6% coarse Al₂O₃ and SiO₂ powders. They promote an increase in friction of the friction material to the recommended minimum value of 0.3. Promising additives also include carbon fiber in an amount of 25–50%, which makes it possible to maintain the wear rate of the composition at a level not exceeding 30 µm/km. By increasing the carbon fiber content to 50%, a minimum value of the friction coefficient was obtained at the initial moment of contact of the tribocoupling surfaces. In this case, the experimental curve of changes in the friction coefficient is characterized by a smooth transition to the slipping region.

During operation of springs, especially cyclic buffer and high-speed springs, there are inevitable relative movements of their surfaces, friction, and coil contacts. Due to friction, a lot of energy is converted into thermal energy, this is а cause of spring wear on the contact points of the coils and of overheating of the machines and mechanisms. The known methods of increasing spring resourcefulness do not consider the issue of friction and wear of springs surfaces contact. Тhe new technologies for increasing the wear resistance of compression springs using contact predeformation are presented in the article. In this case, an additional axial load exceeding the load on the spring in the product by more than 5% and determined theoretically at the stage of development of the technological process is applied to the compressed spring coils into contact. The exposure time under axial load is 1–1.5 s. Serial springs were manufactured and two batches of experimental springs were produced using new technologies. The dispersion of the force parameters of the springs of experimental batch No. 1 as compared with serial springs was reduced by 14.3%, and as compared with experimental batch No. 2 by 42.9%. After cyclic tests the decrease of workload for serial springs averaged 1.17%; for springs of experimental batch No. 1, 0.23%; for springs of experimental batch No. 2, 0.45%. Contact clamping not only promotes the formation of useful residual stresses, but also increases the bearing capacity of the springs. The strip of hardened material is formed, which increases the wear resistance of the contacting surfaces of the coils and reduces friction due to parallel layering. On the contact places of the spring coils, the specific pressure decreases and the deformation wear resistance of the springs increases. Therefore, contact clamping should also be considered as a finishing operation to reduce friction on the places of contact of the spring’s coils and increasing their wear resistance.

The method is aimed at comparing the lubricating capacity of different emulsions. The purpose of the work is to evaluate the possibility of using a universal friction machine, type MMW-1A, to determine the value of the friction coefficient in the cold rolling of very thin strips of carbon steel. The article analyzes the research related to the methods of measuring the friction coefficient in lengthwise rolling. The methodology of experiment determination of friction coefficient value between the material of RCM-1250 reversing mill rolls (steel of working rolls—analog of 60S2HFA steel) and the sample of annealed strip, 0.224-mm thick, made of TS-435 steel grade (analog of 08ps steel, GOST 1050) has been developed. The selected friction conditions are semi-fluid friction. The experiment applied the emulsion, based on the lubricating-cooling liquid, such as Quaker 2185, and used an RCM-125 reversing mill. Two types of ring-shaped samples made of roll material were used in the experiment with wall thicknesses of S = 4 mm and S = 2 mm. The results of the experiments showed that the use of the ring-shaped sample with S = 4 mm is more reasonable from the point of view of stability of the created friction conditions. The recommended average value of friction coefficient between the above materials of rolls and strip was determined: f_cf = 0.038. In the course of the experiment the values of the friction coefficient fluctuated within the boundaries, from the minimum of f_min = 0.012, to the maximum of f_max = 0.048. In general, these experimental results are correlated with reference data on the value of the friction coefficient for this type of rolling and the results of other experiments described in the literature, conducted under similar friction conditions. Proceeding from this, it is possible to draw a conclusion that estimation of the lubricating capacity of various lubricating-cooling liquids, application of universal friction machines of the design described in the article is expedient.