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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 results of research and testing of the technology of strengthening contact surfaces in an oil medium with the addition of fluorinated graphite of the teeth of bevel gears and rolling bearings are presented. The technology provides a significant increase in resource by slowing down the development of fatigue damage to the teeth of bevel gears and rolling bearings of the NK-14ST engine starter drive. [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]

In the process of intense electrical-thermo-mechanical loading of friction pairs of braking devices, which take place on transport, technological equipment, etc., the surface-volume temperatures of their elements can reach significant values, at which the thermophysical properties of the surface and subsurface layers of materials change significantly. Their change is influenced by surface and deep temperature gradients, as well as heating rates and forced air cooling of friction brake elements. Theoretical and experimental studies of the energy load of various types of friction brake units under pulsed and long-term braking modes made it possible to determine the surface and deep temperature gradients, as well as the rate of heating and forced air cooling of the friction elements, and it was established: the most common with local contact of microprotrusions the emerging fields of current lines is the thermodynamic potential, which includes external and internal parameters in their working layers; the thermodynamic potential is determined by the conditions of thermodynamic equilibrium of the tribosystem and the criteria for its stability in a variety of processes accompanied by changes in energy; a local area of actual contact of microprotrusions, formed by the simultaneous action of normal and tangential impulse loads, causing electric and thermal currents that do not completely disappear when the pulsed specific loads are removed, forming frictional connections of microprotrusions; the magnitude of surface and deep temperature gradients and their limitations for metal friction elements, as well as the rates of heating and cooling, knowledge of which allows us to move on to the patterns of changes in the thermophysical parameters of friction pair materials. The regularities of changes in surface and deep temperature gradients and rates of heating and forced air cooling of metal friction brake elements have been established. [ABSTRACT FROM AUTHOR]

The wear process in the tribological system: nitrided titanium alloy - hydraulic fluid - steel is studied. It is shown that the level of wear is determined by tribological structures of the dissipative type, which are self-formed at the evolutionary stage of running-in. Using a linear approximation of the Boltzmann transfer equation, the exponential nature of the running-in stage was established, at which the wear intensity decreases from the initial to the steady-state level and then fluctuates around a constant mean with a constant variance. AMG-10 liquid selectively interacts with the elements. Electronegative elements dissolve in the lubricant, while electropositive elements are transferred to the counterbody, interact with the products of the mechanical destruction of lubricant molecules, and take an active part in the formation of the tribostructure, which reduces the level of direct interaction of the solids in contact. Preliminary laser treatment of titanium alloy activates the process of subsequent nitriding, which makes it possible to reduce the nitriding time while increasing the thickness of the wearresistant nitrided layer. The use of laser pretreatment on real parts makes it possible to increase the service life of friction units and reduce production costs during their manufacture. [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 materials of the article contain questions: thermophysical parameters of friction pairs of braking devices; project calculation and analysis of results; discussion of the results. A generalized method of determining the surface-volume temperature of the friction pairs of braking devices with given design parameters and constant values of the thermophysical properties of their materials is proposed, provided that the friction power corresponds to linear or parabolic laws of change and corresponds to the laws of generating heat flows in friction couplings, which made it possible to establish such. The connection between graphical dependencies for linear and parabolic laws of heat release was carried out through the dimensionless value K as a function of the Fourier criterion (F0), and the dependence of the form K=μ(F0) made it possible to estimate the intensity of cooling of the metal friction element using the Bio criterion (Bi), criterion F0 varied from zero to 1.2, and criterion Bi from zero to 1.0. When determining the surface-volume temperature of the "metal-polymer" pair, it was carried out through the coefficient of distribution of heat flows; while the latter acted on the entire thickness of the metal, and in the polymer overlay only on its surface and subsurface layers. When selecting the material for the metal friction element, the coefficient of thermal saturation was used, which includes the coefficient of thermal conductivity, heat capacity and density of the material, which has a larger value. The generalized method is confirmed by bench data on friction pairs of a belt-pad brake and operational tests of friction pairs of a drumpad brake, in which the material was steel 35ХНЛ-retinax ФК-16Л. [ABSTRACT FROM AUTHOR]

Theoretical and experimental studies of the energy load of a disc-pad brake of a vehicle made it possible to propose a method for determining the components of generated electric currents in metal-polymer friction pairs, based on experimental and calculated data, which is implemented in five stages, at each of which the total electric currents: thermal; the current that arises due to the friction of sliding and contact-interacting macro sections of the surfaces; current arising due to sliding friction, formed by the movement of charged mass transfer particles; the current caused by sorption-desorption processes in the near-surface layers of the lining, which are at a temperature higher than the permissible for its materials, as well as their direction. Determine the total wear during the braking cycle of the friction disc treadmill as the sum of losses due to its oxidation (corrosion) with the involvement of mechanical wear. The components (mechanical, electrical, thermal) of the friction power and their calculated values were determined with the help of the obtained dependencies. Based on the found value of the energy balance of the brake friction unit, the volume intensity of wear of the working surface of the lining was determined based on the obtained dependence with the transition to the dependence of the actual resource, taking into account the width and permissible thickness of the wear of the lining. The projected service life of the pad is achieved due to its working area and length, as well as the specified radius of the microprotrusions of the friction track of the disc. This method made it possible to increase the resource of the friction pad by 1.25 times under different operational parameters of the disc-pad brake of the vehicle. [ABSTRACT FROM AUTHOR]

The relationship between wear and friction properties and the energy load of friction pairs of braking devices during external friction of different friction pairs of a belt-pad brake is considered. The decisive influence on the dynamic coefficient of friction (f) and the intensity of wear (In) of the maximum surface temperature (м) on discrete contacts of friction pairs is shown. Graphical dependences of the form f=f(pa, м)and In =I(pa, м), λ = λ(), а = а() and НВ = НВ() were analyzed (pa - impulse specific loads; λ and а - coefficients heat and temperature, HB - Brinell hardness) and establish their interdependence with the temperatures of the friction surfaces. In a correctly designed metal friction element of any type of braking device, the values of the ratio of the areas of matte and polished (working) surfaces must be maintained. At the same time, the increase in the area of the matte surface is achieved by the introduction of external constructive elements. In drum and belt-pad brakes, this is the implementation of ribs, deflectors, grooves, protrusions, etc.), in disc-pad brakes, internal developed surfaces are used in self-ventilated disks (protrusions, half ribs, ribs, channels, etc.). This approach is connected with the need to intensify the forced cooling of metal friction elements, which are heat energy accumulators in any type of braking device. Therefore, the second and third subsystems of various types of braking devices are considered from the point of view of the interaction of metal friction elements with high-speed flows of the washing medium, which reduce their energy load. When evaluating the intensity of cooling simultaneously with forced cooling in a belt and drum-pad brake, it is necessary to take into account the conductive type of heat exchange in the couplings "pulley rim - fastening protrusion and "drum rim - side wall". The presence of a fastening protrusion significantly affects the intensity of circulation of the main and additional heat flows in the rim of the pulley. The side wall of the drum plays a significant role in forming the thermo-stabilization state of its rim. A comparative analysis of changes in the main operating parameters was made and their interdependence was established on a model belt-pad brake during the operation of friction pairs in pulse and three-shaft braking modes. [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]

A comparative analysis of the performance of mineral and synthetic gear oils according to the main (standard) physical and chemical characteristics was carried out. The main requirements for gear oils, which are formulated today by leading gear manufacturers and are reflected in international specifications and standards, are given. Conclusions were made regarding the compatibility of mineral and synthetic gear oils. [ABSTRACT FROM AUTHOR]

The theoretical and experimental studies of the main physical parameters in the case of superconductivity of a metallic friction element, which is under the unilateral action of thermal, electric and magnetic fields, made it possible to establish the following. The energy of an electron in a crystal lattice cannot take on any values due to the fact that there are sets of discrete energy levels (zones) separated by more or less significant distances. Heat capacity and thermal conductivity have components that relate to electrons and the crystal lattice; the heat capacity in the state of superconductivity turned out to be less than the heat capacity of a normal metal, and the heat conductivity increased due to the local interaction of microprotrusions of friction pairs. In the surface layer of the metal under the action of a magnetic field, a stationary electric current arises, which has its own magnetic field opposite to the applied field, which, as a result, leads to a zero value of induction in the surface layer of the metal. At a critical value of the magnetic field strength, the subsurface layer of the metal friction element goes into a normal state. [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]

An analysis of the existing anti-friction materials used in the friction units of the gas pumping unit as bearing liners was carried out. Taking into account the shortcomings, a new material is proposed in the work, which will be cheaper and have better operational properties. It was considered the characteristics of effect of alloying of metallic die on the processes of generation of tribotechnical characteristics of alloys and coatings on the basis of iron with refractory carbides and borides. It was resulted the technology of alloying of die of eutectic alloys as VTN by the components of bronze Sn-Zn-Pb 5-5-5. It was designed a wearproof antifriction eutectic alloy on the basis of iron for the welding of surfaces of bearing shells, presented it's tribotechnical characteristics and estimated the perspective of using the alloy for shells of sleeve bearings of gas turbine units in place of babbits. [ABSTRACT FROM AUTHOR]

The materials of the article include the following issues: thermal shrinkage of polymer friction lining materials; destructive processes in materials of friction linings; discussion of the results. The increase in the thickness of the friction lining of the brake under bilateral thermal influence depends on the amount and intensity of release of liquid and gaseous products of pyrolysis of the binder (hence, the pressure of gases in the pores of the material close to the surface), as well as on the presence and number of pores in the material, which contribute to reducing the pressure in the pores and reducing the possibility of micro-explosions. The increase in the thickness of the tested overlays in the heated state did not exceed 0.8% (and for some materials it has a negative value), which is significantly less than the recommended values (no more than 2.5%, and for the cooled state no more than 2.0% due to various their rates of flow. Transformation of energy levels of different types of contacts formed by variable contact areas of changing microprotrusions on working surfaces to electrothermomechanical frictional interaction of friction pairs of brakes. Stabilization of lining sizes can be achieved by using a more heat-resistant binder, choosing the optimal composition of components, passing structuring processes during heating and cooling. Thermal treatment of products after forming, introduction of components that prevent the burning of the binder, etc., as well as the creation of compositions with a porous structure of the material. The use of heat treatment in the thickness of the overlay after forming must be thoroughly justified, because the equipment used for it, bulky, lowperformance, very energy-intensive and requires complex equipment for cleaning from harmful secretions. Research conducted by scientists of the companies and other authors show that the presence of a polymer binder in the composition of the friction composition determines the significant influence of the temperature-time factor on the entire complex of physical and mechanical properties, and this influence has a twofold nature. In the deeper and less heated layers of the material, the processes of further structuring and hardening of the binder take place, accompanied by the strengthening of the material with thermal shrinkage. Complex physicochemical processes of oxidative decomposition, cracking and pyrolysis take place on the friction surface under conditions of high temperatures, accompanied by abundant release of liquid and gaseous products. Organoleptically, this is determined by the appearance of a smell, abundant smoke formation and characteristic crackling (micro-explosions). In conditions of difficult removal of gaseous products, due to the close contact of the working surface of the lining with the counterbody, as well as the presence or absence of pores in the material, an increase in the thickness of the lining ("swelling") is possible. In addition, during heating and cooling, the thickness of the lining increases or decreases due to thermal expansion. Thus, the change in the geometric dimensions of the lining is determined by the sum of the dimensions of the change in its thickness, associated with the thermal expansion of the material and the structural changes occurring in the material. [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.)

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.)

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.)

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.)

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.)

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 materials of the article consider the following issues in relation to the problem to be solved: construction of crystal lattices of metals and their parameters; assessment of the state of atoms in the crystal lattice of metal from the standpoint of molecular dynamics; stress-strain state of brake discs and hydrogen wear cells of their working surfaces. In the study of the metal friction element, a model of a multilayer atomic structure in the form of a bellows is adopted, which compresses its corrugations under the action of pulsed specific loads. When the pulse specific loads are removed, the multilayer atomic structure expands due to the internal elastic forces. The previously unknown phenomenon of formation of hydrogen-saturated zones in the near-surface layer of a metal friction element (rim, disk) of a brake device containing in its body "internal" hydrogen circulating between the layers of atoms of crystal lattices, which is that electrothermomechanical friction in a hydrogen-containing medium is the release of "external" hydrogen under pressure due to pulsed specific loads, surface temperatures and their variable gradients in the friction zones. The rate of compression is hundreds of times greater than the rate of expansion of the multilayer atomic structure. Under the action of pulsed specific loads there is a large positive flash point temperature gradient, which in the near-surface layer of the metal friction element turns into a negative surface-volume temperature gradient. This increases the pressure of the injected hydrogen, which is amplified by pulsed specific loads, compressing the multilayer atomic structure. When the pulse specific loads are removed, the multilayer atomic structure expands due to the internal elastic forces. [ABSTRACT FROM AUTHOR]

This work is a comprehensive study of the structure and properties of plasma eutectic coatings after thermal cyclization. This kind of treatment significantly increases the adhesive-cohesive strength of coatings. According to the results of the conducted research, the resistance against the operation of two-layer coatings in the whole temperature range is higher than for single-layer ones. This effect is achieved by the increase in adhesion properties, a decrease in the hardness gradient along the depth of the coating, and the increase in the coating's thermal stability due to the barrier properties of the doped boride layer. By controlling the size of the dispersed crystals of the penetration phases and at the same time the state of the metal matrix, it is possible to select the TCO modes in which the coatings receive optimal tribotechnical properties. [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.)

A review of modern technologies for the deposition of protective wear-resistant coatings for tribotechnical purposes has being conducted. It is established that titanium carbide is widely used to strengthen surfaces as a component of such coatings. We can achieve not only an increase in wear resistance, but also to realize the effect of self-healing of the friction surface. This material is promising for the creation of metal-based composites for high temperature applications. Thus, the tribotechnical properties of the new alloy of the Co-TiC system of tribotechnical purpose are established. Sintered composite alloys based on cobalt matrix (Co alloyed with iron, aluminum and chromium) were made. Titanium carbide was used as a highmodulus strengthening phase. The TiC content was in the range of 30-50 vol. % Porosity was changing in a range of 3.1% to 28%. The melting point of alloys exceeds 1320 °C, and they can undergo all kinds of technological procedures together with the turbine blades, including soldering and degassing, without damage, changes in structure. The research of thermal and structural stability of alloys by methods of differential thermal analysis were carried out. Alloys do not have additional thermal effect, which confirms their structural stability. The study of their microstructure revealed three types of components - TiC particles, matrix solid solution (cobalt-based alloy) and pores - structural defects that have a negative impact on all studied properties. The influence of porosity on the properties of alloys is investigated. It was found that increasing the porosity from 3 to 28 percent reduces the heat resistance by 3 times, while the wear resistance at a temperature of 650 ° C is reduced twice. It is proved that an alloy based on cobalt with 50% vol. TiC and porosity 3.1% is prospective for the material application to the top shrouds of the blades of the gas turbine engine. [ABSTRACT FROM AUTHOR]

The materials of the article consider the thermal stabilization state of the drum rim, which is supported by the contact ionized gaseous medium and moisture desorption products (from the surface layer of the lining) between the double electric layers (polished working surface of the drum the surface of the rim of the drum of the vehicle) - the lower level of the near-surface layer of the overlays). The resulting saturation currents contribute to the inversion of heat fluxes from the polished working surface of the rim of the drum of the vehicle in the near-surface layers of the pads, contributing to its thermal stabilization state. In highly diluted electrolyte solutions, the boundary of the diffusion layer can be displaced beyond the boundary of the so-called slip layer, ie the plane beyond which the movement of the liquid along the interfacial boundary becomes possible. Thus, as the fluid flows along the solid / liquid boundary, the bulk charge moves and, accordingly, a potential difference appears along the fluid flow. The phenomenon associated with the appearance of a bulk charge in the electrolyte solution outside the sliding plane is called electrokinetic. The sliding plane potential is called the electrokinetic potential. Double electric layers in friction pairs play an important role in amplifying the tribo effect in friction pairs of brake devices. The existence of a double electric layer on the interfacial boundary of two media (working surface of the brake drum - the working surface of the polymer friction element), as well as on hot and cold surfaces of the nearsurface friction lining plays an important role not only in ion exchange between friction surfaces. and in the processes of adsorption of ions of the surfaces of brake friction pairs. The presence of a double electric layer significantly affects the electrosurface processes: conductivity, polarization of dispersed particles, mass and energy displacement through charged dispersed systems, electrostatic interaction between charged particles, and so on. In this case, electrosurface processes are components of electrokinetic phenomena that occur in the near-surface layers of friction pads. It is important to note that the basic data on the structure of the electric double layer are obtained from capacitive measurements in the absence of charge transfer through the interfacial boundary. In real operating conditions of molecular electronics devices, the process is complicated: it becomes possible to transfer charges due to electrochemical reaction, ionization of adsorbed particles or change the charge of the electric double layer when the potential is shifted. In this case, the measured capacitance represents not only the capacitance of the double layer, which reflects changes in the charge of the electrode, but also the course of electrochemical reactions on it. The capacitance measured in such conditions can be called polarization capacitance or simply pseudocapacitance. [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]

It is proposed to use a method of gear teeth wear and durability calculation and calculation of conditions of their operations based on phenomenological model of calculation of frictionalfatigue wear during sliding friction. Using the developed method of wear and durability calculation gears, a study of the effect of sliding friction coefficient on durability of two types of straight-cut spur gears under identical working conditions was carried out: with steel gears and metal-polymer couple with polyamide wheels reinforced with carbon and dispersed glass fibers. It also takes into account the change of teeth engagement conditions (two - one - double) and the change of tribocontact interaction conditions as a result of wear. It has been established that the gear with steel wheels has approximately the same durability, as a metal-polymer direct transmissions with a steel pinion and a glass-composite gear in the range of f = 0.17...0.4. The durability of metal-polymer gear made of carbon-composite (direct and inverse) is several times greater than the durability of a metal gearing in the range of f = 0.1 to 0.4. The regularities of the influence of sliding friction coefficient on the durability of gearings are presented. The estimation of the maximum contact pressures in the engagement of these transmissions shows that their largest value will be at the inlet of the teeth in one-sided engagement. There is a very significant difference between their value in transmission with metal gears and metal-polymer transmission. In particular, for metal-polymer carbon-composite transmission, they are smaller about 16 times, and for glass-fiber metal-composite transmission is less in about 18 times. Also, the change in the initial maximum contact pressures due to tooth wear and its regularity was determined. The obtained results are presented graphically, and this illustrates obtained regularities. [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.)

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.)

A study was carried out to determine the effectiveness of increasing the fretting resistance of tribosystems by the formation of discrete-textured oil-based surfaces in the form of regularly located microcavities. Phenomonologically, such surfaces were considered as discrete-textured, and micro-depressions - as reservoirs, providing a permanent regeneration of the boundary lubricating layers in the zone of frictional contact. The formation of discrete-textured surfaces in the form of a system of hollow pyramidal and spherical microcavities with given texture parameters on the sample working surfaces was carried out by the method of shock-plastic deformation. The friction pairs with different location of materials in pairs according to hardness were studied. The pairs with discretely textured surfaces formed on a sample harder than the counterbody conventionally referred to as direct pairs. The pairs with discrete-textured surfaces formed on a sample of lower hardness than the counterbody hardness were called inverse pairs. It has been established that in the case of friction of polished surfaces in accordance with the accepted conditions, lubrication does not provide a significant increase in the fretting resistance of the investigated materials in both direct and inverse friction pairs, which testifies to insufficiently high resistance of the boundary lubricating layers on such surfaces. Under the same conditions of fretting and lubrication, the resistance to fretting-corrosive wear of friction pairs with discrete-textured surfaces has increased significantly. The greatest effect of wear resistance increasing is achieved in direct pairs with the spherical microcavities profile. Compared to the base version the absolute value of wear of samples with spherical microcavities profile in direct pairs decreased by more than 6 times. At the same time, the counterbody wear and the total wear of pair also decreased noticeably. It is obvious that according to the accepted parameters of discrete-textured surfaces formation and parameters of fretting, the spherical profile provides the greatest lubricating efficiency of the microcavities compared with the prismatic profile. According to the results of the experiment, a statistical analysis was carried out and the regressive models of the dependence of wear on technological parameters of the discrete-textured surfaces formation and fretting parameters were developed. [ABSTRACT FROM AUTHOR]

The role of certification tests in the assessment of the compliance of friction units of aviation and space technology is shown. Brief explanations are given on the explanation of the quality of triboelements and their controlled characteristics. On an example of evaluating the quality of coatings of friction units, the possibility of constructing a mathematical model for taking into account the corresponding groups of coating properties as components of quality indicators is shown. Analysis of types of quality control of friction surfaces, in particular their coatings, allows you to determine the specific significance and consumer properties of the monitored indicators. The methodical supply of the types of evaluation of the quality of the friction units is determined. Analytical dependencies that define the boundaries of the practical use of the constructed model, the estimation of the generalized quality index are presented. Identification of factors that affect the provision of established quality indicators and the establishment of ways to target these factors will reduce and optimize research on improving the quality of friction surfaces. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State 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.)