Search

The nature of the stress state arising under sliding friction loading is investigated on the model of a discretely processed material in which there is an annular transition zone between the inclusions (hardened area) and the matrix according to the known law of change in its mechanical properties. It is shown that local stresses in the material, depending on the type of loading of the elementary volume, can be predicted and calculated, taking into account the mechanical properties, appearance, and structure of the transition zone that occurs as a result of laser processing. The strength of the transition zone has a linear dependence and the stress concentration in the area after laser treatment decreases and smoothly transitions to the matrix, and then it decreases to the stresses in the matrix, which gives the advantage of discrete laser treatment of hardened steel. [ABSTRACT FROM AUTHOR]

The thermodynamic analysis of the interaction of composite powder alloys of the Co-TiC system with air is carried out. The main regularities of their oxidation are established. The mutual influence of the content of chromium and titanium carbide on the quantitative composition of oxidation products is shown. Based on the analytical studies, the dependence of the quantitative and qualitative composition of the products of interaction with air of powdered alloys of the Co-TiC system on the ratio of their components was determined. The formation of protective layers can be predicted, and their formation can be controlled by selecting appropriate alloying elements and strengthening phases by thermodynamic analysis. The general laws of oxidation of powdered composite alloys of the Co-TiC system have been established. The influence of chromium content in the material on the composition and properties of oxide layers is shown. It was found that at a high chromium content in the matrix (more than 25% by volume), the brittleness of the oxide layer increases, which will lead to its intensive wear. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies of the wear process of detonation coatings and counterbodies and compares them with other types of coatings, obtaining wear characteristics. The characteristics of wear of coatings are described in an analytical form, as well as the results of the study of tribological structures. The tribotechnical characteristics of detonation coatings are determined, taking into account the properties of dissipative structures that are self-formed in contact with friction. The effectiveness of the method of researching the process of wear of detonation coatings has been determined. It has been established that when coatings are rubbed against chrome, the total wear of the friction pair is significantly less than when rubbed against bronze. This is due to the best tribotechnical properties of chromium in the experimental field. The coefficient of friction of electrochemical chromium coatings is of the same order as when rubbing on bronze. The total intensity of wear of the coating and the counterbody when rubbing against chrome is somewhat lower than when rubbing against bronze. Since tribological structures are formed from complex oxides, asphaltenes, cokes, etc. during friction of coatings on chrome alloy VT-22, therefore the tribotechnical characteristics of such systems are somewhat lower than in systems that include bronze. [ABSTRACT FROM AUTHOR]

The structure, phase and chemical composition, microhardness, and microbrittleness of the surface zones of P6M5 steel after chemical and thermal treatment: nitriding followed by titanium and chromium plating are considered. Metallographic and micro-X-ray spectral analyzes of wear surfaces of P6M5 steel with different types of coating were carried out. It is shown the dependence of physical and mechanical properties of complex coatings and discrete laser treatment on wear-resistance. The analysis of the obtained data showed that azochromic coatings with additional strengthening by laser treatment of steel, which serves as a substrate for coatings, increase its performance in extreme operating conditions, excluding its crushing, chipping and peeling. [ABSTRACT FROM AUTHOR]

The article considers the efficiency of applying electric spark coatings with the aim of studying the effective influence on the tribological properties of eutectic alloys. Friction and wear tests of electrospark coatings made of the developed eutectic alloy on a steel substrate were performed. In order to compare the effectiveness of the influence on the tribotechnical properties of eutectic alloys, both the coatings in the initial state and the coatings annealed under two different modes were tested. Based on the results of the study of the chemical composition of the films formed in the process of friction, regularities were established by qualitative assessment. The dependences of tribotechnical properties for the initial and heat-treated coatings were determined. These studies indicate the feasibility of using electrospark coatings for different friction conditions. [ABSTRACT FROM AUTHOR]

The influence of the thermodynamic state on the form processes of tribotechnical properties eutectic coatings on the iron base containing refractory carbides and borides are considered. Coverage was received KIB and gas-thermal methods, which ensured a high rate of heating eutectic coatings, a short time for the creation of the melt and the subsequent rapid cooling on a relatively cold substrate until the appearance of non-equilibrium states, which are manifested in the form of a change in the mechanism of eutectic crystallization. It was established that in the studied eutectic coatings, non-equilibrium phases are formed at the same time as equilibrium phases. It is shown that the ratio between these phases, as well as the structure and, therefore, the tribotechnical and corrosion properties of the obtained eutectic coatings can be controlled by annealing. High-temperature diffusion annealing leads to a change in the phase composition of coatings and their structure, and also changes the chemical activity of the structural components of eutectic coatings with the formation of oxide films. In the friction pair, they play the role of a solid lubricant, which can effectively reduce the wear of not only the coating, but also the friction pair as a whole, which allows to expand the range of tribotechnical tasks related to reducing the total wear of the friction pair in conditions of extreme friction. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The possibilities of the method for the numerical solution of high-order differential equations for solving tribology problems are shown. In particular, the problem of deformation of a section of a wheel during rolling is considered, taking into account the contact zone. The technique for solving the problem is based on the general use of the parameter continuation method and the Newton-Kantorovich method, it describes the spatial nonlinear deformation of an elastic element of arbitrary curvature with an arbitrary vector of acting static or quasi-static loads, while this article considers only the plane problem. Methods of representation of loads on the section under consideration are given. Also considered is the consideration of the variability of the line of contact of the wheel, depending on its deformation. To illustrate the method, an example of solving the problem from determining the stress-strain state of a wheel during rolling is given, taking into account the plane of contact with the supporting surface. The given graphs are built automatically using application programs that solve the problem. The described algorithms allow, in contrast to the previously known ones, to solve fundamentally new types of problems of elastic deformation of triboconjugation elements, to unify the types of structures that are investigated, to efficiently switch from one design scheme to another depending on physical and geometric parameters and load conditions, to obtain output data in user-friendly form. Determination of the factors that affect the provision of the established parameters of the tribo-conjugation and the establishment of ways of purposeful management of these factors will reduce and optimize the study to improve their quality. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The analysis of the state of the problem with the development of wear and durability calculation methods of metal, metal-polymer and polymer gears is presented. Known methods in the literature are characterized for gears with metal wheels. The basic author's method of calculating cylindrical gears has been provided. Impact factors were described by which modified gear calculation methods were formed based on the basic method. These are the following factors: operational - change in the curves of involute teeth profiles due to their wear, structural - parity of the teeth, technological - correction of teeth, tribological - wear resistance of materials. According to the developed methods, the estimation of contact pressures, wear and durability of spur and bevel straight and helical gears, worm gears made of metal structural materials was carried out. The modified method was used to calculate a spur straight-tooth metalpolymer transmission (hybrid transmission) with steel gear and a glass or carbon fiber reinforced polyamide wheel. [ABSTRACT FROM AUTHOR]

The paper presents the research results of friction fracture processes with an example of composite electrolytic coatings. With the methods of analysis of theoretical and experimental results of the study using the energy model of the wear particles formation in near-surface zones of friction pairs is made by evaluating the process of the layers surface destruction. The presence of the dependence of the wear particles size on the material mechanical properties has been established. The results analysis of coatings durability is executed. It is established that the condition of the coating destruction in the process of friction is determined by its mechanical properties and is achieved faster for wear particles with larger sizes. The size of the wear particles is smaller in the case of a material with higher hardness (with a large value of Young's modulus of elasticity), but larger -in a material with greater strength (large values of specific energy of cohesion).The minimum resistance wear corresponds to the optimal content and the size of the filler, when the grain size of the filler corresponds to the size of the wear particles. If the size of the filler grains becomes larger than the average particle size of the wear characteristic of this saturation level, the particles of wear will be the filler grain (TiB2). The nature of wear becomes more abrasive and wear is growing. It is theoretically grounded and experimentally proved that for an equal specific cohesivity of SiC (12.68 eV) and TiB2 (13.51 eV), it is advisable to choose a filler with higher hardness SiC (392 GPa), TiB2 (530 GPa), respectively the ratio of Young's modulus of elasticity and specific energy of cohesion forSiC = 31.25, for TiB2 = 39.23. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Questions of dependence of wear intensity of friction pairs material on the scheme and the contact size of friction pair elements, and also on the amplitude-loading fretting parameters are considered. The research was carried out on samples made of titanium alloys VT20, VT8, VT22 and aluminum alloy D16T in accordance with the "plane-cylinder" contact scheme and the plane annular contact of continuous and discontinuous ring with cylinder end face. Analysis of results of comparative tests by the "plane-cylinder" contact scheme of samples made of alloys VT20, VT8 and D16T showed that the increasing of the surface relative strengthening parameter leads to the wear intensity increase. The mechanism of formation of protective secondary structures on the friction surface was investigated using by electron microscopic and X-ray spectral analyses. The critical fretting amplitude above which the wear intensity increases sharply is lower for the type of contact, which provides better possibilities of wearing products removing from the friction zone. [ABSTRACT FROM AUTHOR]