Problems of Friction and Wear

ANALYSIS OF SIGNALS OF ACOUSTIC EMISSION OF TRIBOSYSTEM IN CONDITIONS OF STEPPED LOAD INCREASE

2024-03-30T03:20:20+02:00

An evaluation of the performance of electric spark coating in conditions of stepped load increase was carried out based on the analysis of acoustic emission (AE) signals. The purpose of the research was to determine the changes in the frictional contact during the transition of the tribosystem from the normal to the catastrophic stage of wear. The research was carried out for tribosystem steel 30ХГСА - unmodified or modified Д16 duralumin alloy. Modification was carried out by applying a combined discrete coating of hard alloy ВК8 and copper with a density of 55-65% by the method of electrospark alloying. Modification of Д16 duralumin provides efficient operation of friction pairs up to 1200 N, the average power of AE signals and their dispersion values are reduced by 2...4 times. An 80% reduction in wear intensity of tribosystems with combined electric spark coating was established, the depth of propagation of plastic deformations is reduced by 2 times. Empirical dependences of wear intensity on loading parameters and AE signals were obtained.

INCREASING THE EFFICIENCY OF TECHNOLOGICAL PROCESSES OF DRAWING AND ROLLING IN CONDITIONS OF RATIONAL USE OF DRY AND SEMI-LIQUID FRICTION FORCES UNDER THE INFLUENCE OF EXTERNAL VIBRATIONS

2024-03-30T02:50:58+02:00

In modern technological processes of metal forming, such as cold rolling, rolling and drawing, a significant proportion of energy supplied to the rolling device is irretrievably lost to friction and wear, as well as giving the workpiece a given shape (or dimensions) as a result of plastic deformation.

To assess the nature of friction in such machines, the types of frictional interaction between the material of the processed workpiece and the tool were determined, taking into account the influence of lubricants. As it was established, during metal pressure treatment, there is both "dry" and "semi-liquid" friction. Even in the presence of lubricant in the kinematic pair: fiber-wire billet dry friction prevails. As practice shows - the occurrence of significant friction forces and forces of tension of the workpiece is caused by the presence of multiple deformation microroughnesses in the receiving part of the fiber, at its interaction with the moving workpiece. These microroughnesses (on the workpiece) are sheared and plastically deformed by the interaction of the contacting pair. Moreover, this deformation process is accompanied by a continuous wave background in the sound range.

For intensification of rolling and drawing processes it is recommended to use, by analogy with vibration metal cutting treatment, vibration rolling and drawing, by installing additional vibrators acting in the direction of rolling or drawing on the applied fibers. The proposed vibrators operate, as a rule, in the ultrasonic range. Optimization of the rolling (drawing) unit operation is carried out by selection of amplitude and frequency of additional vibration, providing the required mode of machine operation, which realizes the transition from "dry" friction between wire and die to "semi-liquid" friction.

Implementation of measures on creation of additional devices for ultrasonic drawing and rolling allows to reduce energy costs of the rolling and drawing operation, as well as to increase the wear resistance of the tool.

STUDY OF THE DYNAMICS OF SPINDLE SHAFT ON GAS-STATIC BEARINGS

2024-03-30T02:23:06+02:00

This study delves into the complex dynamics of spindle shafts mounted on gas-static bearings, employing computational experiments and analysis to reveal crucial insights for optimizing high-precision machining processes. We identify natural frequencies and resonant tendencies of spindle vibrations through advanced Finite Element Method (FEM) simulations, highlighting their impact on operational stability and machining quality. Deliberately introduced imbalances further illuminate the dynamic behavior, displaying the detrimental effects of resonance on spindle performance. To mitigate these effects, we explore various technical solutions, including reducing rotor imbalances and intensifying acceleration through critical regions. Ultimately, this investigation provides a comprehensive understanding of spindle dynamics on gas-static bearings, guiding the development of robust and high-precision spindles for a range of industrial applications beyond just machining, such as precision robotics and microfabrication.

INFLUENCE OF FLUOROCARBON COMPOUNDS ON ANTI-FRICTION AND OPPOSITE PROPERTIES OF TRICOMPOUNDS

2024-03-30T02:08:13+02:00

The results of the study of the influence of fluorocarbon compounds of the type (СХ)n on the antifriction and antiwear properties of tribocompounds are presented. It is shown that in conditions of extreme lubrication of gears and bearings, these compounds have good prospects for use as additives and additives to oils. Mechanisms of lubricating action and some examples of practical application are considered. The developed methods of using carbonofluorides include running-in of friction nodes in environments that contain carbonofluorides, introduction of carbonofluoride additives in oils, plastic lubricants, lubricating-cooling and hydraulic fluids. Approbation of these methods in friction nodes of gas turbine engines (GTD) showed the prospect of their wide use in aviation technology. The most important results of the test are that in the presence of carbonofluorides, the service life and maximum allowable contact stresses of rolling bearings and gears can be significantly increased, and after the introduction of carbonofluorides, the friction nodes become less sensitive to the quality of lubricants.

DEVELOPMENT AND MODERNIZATION OF A COMPLEX OF INSTALLATIONS FOR WEAR TESTING OF METAL-POLYMER COMPOSITE MATERIALS FOR SPHERI-CAL SLIDING BEARINGS

2024-03-30T01:46:09+02:00

The fretting corrosion machine has been modernized for testing spherical bearings under vibration conditions. The method of research of anti-friction composite materials and coatings for low-frequency reversible movements has been developed. A method for laboratory resource tests of aviation spherical sliding bearings with metal-polymer composite materials in conditions close to real has been developed.

OF THE SERVICE LEVEL IN AN AIRCRAFT MAINTENANCE ORGANIZATION BY GROUP QUALITY INDICATORS

2024-03-30T01:00:45+02:00

The article presents the results of a comparative analysis of the assessment of the efficiency of three aviation enterprises: AVIATECH LLC, SPC MS AVIA-GRADE LLC and AIR SERVICE LLC by quality indicators. These organizations provide aircraft maintenance services. The average quality assessment in an aircraft maintenance organization is calculated as the arithmetic mean of group quality indicators for each maintenance organization. It is proposed to assess the level of service quality by an integral quality indicator. The integral indicator is the final indicator of the service quality, calculated on the basis of a set of quality assessments of various components of the processes of activity of aircraft maintenance organizations obtained in the process of monitoring.

REGULAR WEAR DETONATION COATINGS ON TITANIUM ALLOY VT-22

2024-03-21T03:30:47+02:00

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.

BEARINGLESS ROTOR SYSTEM MAIN COMPONENTS DESIGNING

2024-03-21T02:27:29+02:00

Bearingless rotor system design optimizes mechanical simplicity, eliminates frictional losses typical of conventional bearing systems, and improves the overall efficiency of the rotor system. Based on the findings of the research, it is possible to determine that composite materials can be applied in order to improve the performance of the rotorcraft rotor system.A theoretical analysis of the influence of input parameters on the aerodynamic quality of the main rotor of a rotorcraft was carried out. The strength and aerodynamic quality of the designed parts were calculated using the finite element analysis method. The energy efficiency of the use of composite materials is substantiated, which will ensure better efficiency and competitiveness of the aircraft.

GENERALIZED METHOD OF DETERMINING THE SURFACE-VOLUME TEMPERATURE OF ELEMENTS OF FRICTION UNITS

2024-03-21T00:42:09+02:00

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 drum-pad brake, in which the material was steel 35ХНЛ-retinax ФК-16Л.

COMBINED METHODS OF ENGINEERING OF CONTACT SURFACES OF TRIBOLOGY SYSTEMS

2024-03-21T00:20:41+02:00

The issues of ensuring the durability and reliability of equipment, increasing wear resistance and expanding the range of operation of friction pairs in extreme operating conditions require solutions related to innovative technologies for the formation of wear-resistant surfaces that can significantly increase the efficiency of using hardening methods, creating new ones and improving existing ones.

A brief review of the combined methods of engineering contact surfaces of tribological systems is carried out. The perspective of using this direction to expand the range of use of discrete protective structures, namely in the conditions of fretting, fretting fatigue, and limit friction, is shown.

INFLUENCE OF HIGH-TEMPERATURE LOADING CONDITIONS ON CHANGES IN THE PHYSICAL STATE OF YTTRIUM-CONTAINING COATINGS

2024-03-13T10:07:35+02:00

yttrium content varies linearly and significantly differs from the nature of the mass gain under the conditions of modelling dynamic loading in a burning iso-octane-propane-butane gas mixture at a temperature of 950-1020 ℃. It is determined that the maximum mass increase for gas-flame coatings under static loading is 30-35% at the yttrium concentration of 0.3-0.5%. However, for ionoplasma coatings with the same yttrium concentration, the mass gain is almost 2 times less than that of gas flame coatings. Comparing the peculiarities of changes in the rate of increase in the mass of coatings under dynamic conditions of high-temperature loading, a graphical model of changes in the physical state of coatings was obtained, according to which the minimum amount of secondary compounds will occur at the gas-flame method of formation with a yttrium concentration of 0.1% to 0.47%, at the ion-plasma method of formation with a concentration of 0.25% to 0.35% (under conditions of a slight increase in oxygen in the interaction medium). It was determined that, without taking into account the time of structural-phase transformations and chemical reactions, the weight gain of coating materials under static loading is much greater than under dynamic loading.

SUBSTANTIATION OF EXPEDIENCY OF USE OF TOOL HIGH-SPEED CUTTING STEELS AS COATINGS IN FRICTION UNITS

2024-03-12T23:57:48+02:00

The analysis of modern researches in the field of composite materials on the basis of tungsten carbide used as surfacing materials is carried out. In particular, the influence of morphology of carbide phase on wear resistance of materials is analyzed. Particular attention is paid to the analysis of conducted studies of ultrafine and nanograined composite materials, their comparative analysis with conventional micrograin coatings. The expediency of research of application of tool high-speed steels as coatings, applied by vacuum electron-beam processing method, which allows to organize micro-metallurgical process with minimal impact on the base metal and possibility to form hardened layer, the thickness of which is adjustable within wide limits, is substantiated.

WAYS TO SOLVE THE PROBLEM OF GAS-FLAME SPRAYING OF GLASS-ENAMEL COATINGS

2023-12-12T01:20:51+02:00

Based on the analysis of the gas-dynamic model of two-phase flow in thermospray plants, the temperature of gas and particles was estimated, as well as the analysis of the heat exchange process in the system "extended flare-powder particles with low thermal conductivity", the possibility of spraying enamels by gas-flame method An analytical assessment of the thermal state of enamel particles in the torch and at the time of contact with the substrate is given. The values of glass enamel particle and gas phase temperatures along the torch axis are theoretically determined. It is established that glass enamel particles cannot be softened in the flame of known thermal sprays due to the short length of the high-temperature zone of the torch. Theoretical analysis of the heat transfer process in the system "flare-particles of powder with low thermal conductivity" (for example, powders of glass enamels) showed that to soften them it is necessary to increase the duration of the powder in the flare. A method of gas-flame spraying with an elongated torch based on the formation of a secondary torch due to the use of the effect of combustion with separation is developed. Analytical evaluation of the thermal state of enamel particles in the torch torch and at the time of contact with the base showed the possibility of spraying powders of materials with low thermal conductivity by the gas-flame method by increasing the length of the torch / To increase the length of the torch, it is proposed to form a secondary torch at a distance from the nozzle of the thermospray and theoretically determined the distance of formation of the secondary torch.

INTERPRETATION OF ENERGY METHODS IN THE THEORY OF FRICTION AND WEAR FROM THE STANDPOINT OF CONTINUUM MECHANICS AND DISLOCATION THEORY

2023-12-11T06:31:02+02:00

In modern tribotechnical calculations, a significant role is played by theories of friction and wear based on the energy of processes occurring on the outer layers of interacting parts. Thus, the energy approach allowed us to formulate the view that under dynamic loading of two elastic bodies, as a result of friction, part of the energy is reversible and goes to the development of elastic vibrations, another part of the energy of inelastic interaction of parts, at the molecular level, is redistributed to other types of energy and dissipated in the form of thermal energy into the environment, while the remaining energy, in the case of vibrations of surface layers, accumulates as an irreversible part of the potential energy in deeper layers of parts. This energy, when a certain threshold value is reached, contributes to the destruction of the surface and subsurface layers of the friction pair elements. Taking into account the temperature effects of friction has allowed a number of researchers to determine friction coefficients and forces based on the hypothesis of the formation of welding bridges during metal friction and their subsequent destruction. In addition, hypotheses about the diffusion of atoms during the friction of kinematic pair elements, as well as the hypothesis about the possibility of recrystallization of metals (and other materials) at room temperature, have become widespread. As a generalization of the results of the hypotheses considered, the author of [1] proved that the friction process has a dual nature and can be described by the molecular mechanical theory of friction and wear. The existence of a significant number of hypotheses and theories of friction and wear as physical phenomena is due to the convenience of the energy approach and the extreme complexity of the process itself. The proposed work is aimed at clarifying and, in some cases, simplifying tribotechnical and related thermal calculations.

STATISTICAL ANALYSIS OF THE RESULTS OF STUDYING THE TRIBOTECHNICAL CHARACTERISTICS OF LUBRICANTS UNDER FRICTION

2023-12-11T06:06:10+02:00

Effective lubricants play a crucial role in ensuring machinery's smooth operation across diverse industries like aviation, engineering, and automotive sectors. Their significance lies in enhancing operational efficiency, reducing downtime due to equipment breakdowns, and extending machinery lifespan. These lubricants primarily target friction and wear reduction, thereby increasing intervals between maintenance and repair cycles in various equipment. The research aimed to evaluate the specific parameters impacting wear in friction pairs, focusing on the lubricating antifriction and anti-wear properties of Aero Shell Grease 33 and VNIINP-286M. Using an СМЦ -2 installation, real-time monitoring of tribocontact indicators like friction torque, roller speed, and lubricant temperature was conducted. The study considered non-stationary friction conditions, varied contact loads, and different lubricant application methods to prevent boundary lubrication. Statistical processing via Statgraphics Centurion software involved regression analysis and ANOVA. Regression models correlated wear with variables like friction work, lubricant layer thickness, friction coefficient, contact load, and penetration. Stepwise regression eliminated non-significant variables, refining the predictive model's accuracy. ANOVA validated the model's significance. The outcomes highlighted variables like load and friction as significant contributors to wear in friction pairs, leading to a more comprehensive understanding of lubricant performance in various operational conditions. The study emphasized the practical applicability of statistical tools in optimizing lubricant efficiency and machinery reliability, shedding light on key variables driving wear behavior in friction systems.

RESEARCH OF CAVITATION EROSION OF STRUCTURAL MATERIALS

2023-12-11T05:48:06+02:00

The results of experimental studies of the patterns of wearing of structural materials which are used in the hydraulic machine design engineering under the impact of hydrodynamic cavitation are presented. It is proposed to use a throttle device working in the mode of developed cavitation and being the throttle generator of cavitation pressure fluctuations, as a cavitation generator in studies of the cavitation resistance of structural materials. The rational type of throttling device for creating the liquid’s cavitation flow has been established based on the analysis of flow and differential characteristics of throttling devices of various schemes, which work as throttle cavitation generators of pressure fluctuations. It is proposed to use the dimensionless pressure drop on the throttle cavitation generator of pressure fluctuations as a cavitation criterion. The peculiarities of generation of the cavitation pressure oscillations by a throttle generator have been studied. The regularity of the influence of the pressure drop on the throttle cavitation generator of pressure fluctuations (mode of operation) on the range of cavitation pressure fluctuations and the amount of cavitation wear has been established. The influence of the geometric parameters of the throttle cavitation generator of pressure fluctuations on the intensity of the cavitation erosion was determined. Analytical dependences of the rate of cavitation erosion of test samples of materials on the pressure at the inlet to the throttle cavitation generator of pressure fluctuations were determined.

The results of the experimental research can be used to create highly efficient throttle cavitation generators of pressure fluctuations for the study of the cavitation erosion, cleaning the parts from contamination, intensification of technological processes in the chemical, oil production and other industries. On the other hand, the obtained results make it possible to create the hydraulic units that will have the high resistance to the cavitation erosion.

STRENGTHENING AND INCREASE OF WEAR RESISTANCE WORKING BODIES OF AGRICULTURAL MACHINERY

2023-12-11T04:07:30+02:00

The influence of the surfaces of the working organs of agricultural machines with a discrete structure coating, which has a relief in the form of hemispheres, on the destruction and grinding of grain raw materials is considered. It is shown that the working surface of cutting and crushing elements covered with a discrete structure and with a relief in the form of hemispheres can be more effective when grinding grain raw materials. The theoretical rationale and results of experiments in grinding wheat grain with cutting and crushing elements having a working surface covered with a discrete structure are presented. The article discusses the influence of the working surface of crushing elements with a coating of a discrete structure having a relief in the form of hemispheres located on a plane on the destruction and grinding of grain raw materials during its free impact. It is shown that the working surface of crushing elements coated with a discrete structure with a hemispherical relief, not yielding to a plane in a direct impact, can be much more effective in grinding grain raw materials if the angle of incidence of grain is increased. The theoretical justification and experimental results are given for grinding wheat grain by crushing elements with a working surface with discrete structure coatings. It is justified that in order to increase the wear resistance of the working surfaces of the grinding elements, the material of the discrete coating must have a hardness that is much higher than the hardness of the main material. The combination of the viscosity of the base material and the high hardness of the coating areas ensures the durability of the grinding elements.

ANALYSIS AND INTERPRETATION OF WEAR IN POLYMER MATERIALS BASED ON TRIBOLOGICAL INVESTIGATIONS

2023-12-11T03:44:17+02:00

The analyzed properties of polymer materials related to wear resistance and vibration absorption capabilities, utilized in the production of sliding pairs, have been explored. The perspective of employing polymer-metal friction pairs in industrial machinery, pharmaceuticals, and the food industry has been substantiated. To effectively control any mechanical system with sliding motion under optimal parameters, indicating tribological characteristics for materials in frictional contact is a convenient means for swiftly characterizing tribological behavior when operating conditions are variable. Through experimental investigation, factors influencing the wear of polymer specimens in contact with metal have been analyzed. The materials subjected to tribological analysis are polymer materials such as Sustamid 66 gray, Sustapei, and SusTamid 6G OL, manufactured by the Röchling Group, in contact with steel 30KhGSA. All selected polymer materials are designed for use in pairs with sliding contact.

INFLUENCE OF MAGNETIC FIELD ON THE ANTIWEAR PROPERTIES OF DIESEL FUELS REFORMULATED BY BIOCOMPONENTS

2023-12-11T03:28:45+02:00

The article discusses the issue of antiwear properties of traditional and alternative diesel fuels. The main goal of this work was the theoretical and experimental studies on the effect of alternative biodiesel fuels (on a plant basis) on the change in the antiwear properties of traditional diesel fuels. Also, the goal was to study the effect of the magnetic field on the antiwear properties of diesel and alternative diesel fuels. Experimental studies have been conducted for the antiwear properties of traditional and alternative diesel fuels based on biocomponents obtained from rye oil. The studies showed that the addition of methyl esters of fatty acids of rye oil led to an increase in the amount of wear by 1.8 (10% esters) and 2.2 (20% esters) for the diesel samples and their mixtures with biocomponents, respectively. During the treatment of fuels with a magnetic field of 0.1 T and 0.4 T, it was established that the amount of wear is 1.2 and 1.5 times (10% esters, a magnetic field of 0.1 T and 0.4 T, respectively); 2.2 and 1.15 times (20% esters, magnetic field of 0.1 T and 0.4 T, respectively) times, respectively. It was established that the treatment with a magnetic field stabilizes the antiwear properties of diesel fuels in the case of addition a biological component to them. The results of studies can be applied in the chemical industry, the transport industry, in particular, in the operation of diesel vehicles. The article results can be useful to tribologists, chemical experts, as well as scientists involved in the development and implementation of alternative engine fuels.

EVALUATION OF THE EFFICIENCY OF THE LUBRICATION OF OILS WITH CARBONFLUORIDE ADDITIVES IN NON-STATIONARY FRICTION REGIMES

2023-12-11T03:02:57+02:00

The results of the study of the effect of carbonofluoride additives on the lubricating effect of aviation oils VNIINP-50-1-4u, IPM-10 are presented; MS-8p, industrial oils I-20A, IGP-18 and automotive oil M-10G2K in non-stationary friction modes. The introduction of KF additives into lubricating media significantly reduces, and in some cases completely eliminates, the temporary deterioration of the lubricating effect in non-stationary modes due to the high adsorption properties and chemical activity of carbonofluorides.

RESEARCH OF COMPOSITES FEATURES BY SOLVING THE DIRECT AND INVERSE PROBLEMS OF THERMAL ELASTICITY

2023-12-11T02:29:14+02:00

The article provides an analytical solution to the three-dimensional coupled problem of thermoelasticity for a composite whose structure and possible defects are given by trigonometric polynomials. Parameters of the temperature field arising as a result of defects in its structure are used in the diagnosis of defects in its structure. This is of great importance and practical value for non-destructive testing tasks. An expedient way of finding temperature values as a function of time and geometric coordinates is also the solution of inverse problems of thermoelasticity, i.e. determination of the temperature field based on the field of temperature stresses. The economy of this method lies in the fact that its application makes complex experimental studies of technical objects cheaper and eliminates the need to create computational and analytical methods that accompany these studies.

EVALUATION OF THE FRICTION PAIR RESOURCE OF DISC-PAD BRAKES OF VEHICLES

2023-12-09T23:08:52+02:00

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.

FORMATION OF ANTIFRICTION SURFACE STRUCTURES UNDER FRICTION

2023-09-27T20:02:35+03:00

The results of the formation of anti-friction surface structures of the developed glass-composite self-lubricating nanocoatings, the structural components of which have a qualitative effect on the graphitization process and ensure the production of a surface layer of α-graphite that minimizes contact parameters, are presented.

The positive role of the glass phase in the form of aluminoborosilicate, which affects the tribotechnical properties of coatings, has been established. It is noted that the increase in adhesive strength is achieved due to the formation of a surface layer of vitreous sodium silicate during sputtering. It was established that the intercalation of the graphite layer with particles of the subsurface zone does not significantly affect the tribotechnical characteristics. The developed nanostructured glass composite coatings showed high anti-friction characteristics in the entire load-speed range of tests.

THE RESEARCH OF IMPROVEMENT WAYS FOR PYROLYSIS GAS COOLING AND BLOWING PROCESSES IN PYROLYSIS GAS POWER STATIONS USING CONVENTIONAL TECHNICAL SOLUTIONS

2023-09-27T19:52:09+03:00

The article is dedicated to describing the research of different ways, appliances and solutions for flammable gas supply, transportation and cooling, performed in terms of authors’ PhD theses, related to pyrolysis gas production and application for electric power production. The main idea of this research is the investigation of opportunities of application of modern simple generally used technological solutions on pyrolysis gas power plants for the above mentioned units design. The research is related to different ways of pyrolysis gas cooling and also to the ways of the gas supply from gas generator to the consumer. Another goal is to create a systematic approach to the automation of pyrolysis gas production and transportation onto future pyrolysis gas powered electric power plants.

SIMULATION OF TRANSPORT AND LOGISTICS SCHEMES OF TRUCK TRANSPORTATION UNDER THE CONDITIONS OF GLOBAL RISKS

2023-09-27T16:27:01+03:00

As a result of the increase in the number of factors that ensure the efficiency of transport flows, the methods of building mathematical models, which are based on the consideration of general laws, turned out to be ineffective. Therefore, it is promising to involve experimental methods of identification based on the formalization of the results of observations and analysis of the arrival of new information about changes in the situation that has developed with the use of new digital technologies.

The article shows that in the near future, road connections together with water transport will be of key importance, and therefore the task of mathematically ensuring the management of the preservation of traffic flows under the conditions of global risks will always be relevant. The method of work is the modeling of traffic flows under conditions of preservation of global risks.

A solution to the problem of maintaining the dynamics of traffic flows caused by the pandemic, military actions and extreme situations is proposed. Based on graph theory, Ford-Falkerson and Dinitz algorithms, a modified algorithm for determining the structure of transportation was developed. A feature of the algorithm is the synchronization of the capacity of transport flows with the moments of lifting and introducing restrictions on transport. The novel proposed algorithm is the possibility of adjusting transport routes. Also, a new use of the proposed modified algorithm is the synchronization of technologies using the methodology of determining the throughput capacity of the branches of the implementation of transport flows with moments of the concept and introduction of restrictions due to unforeseen situations and global risks. The modified algorithm for determining traffic flows in the conditions of unforeseen situations and global risks based on the maximum algorithms of Ford-Falkerson and Dinitz ensures the minimization of losses of carriers and traffic flow. Implementation of the algorithm ensures maximum traffic flow in extreme conditions and global risks.

STUDY OF THE PROCESS OF RECOVERY OF IRON OXIDES BY HIGH-TEMPERATURE HYDROGEN-CONTAINING GAS IN AN ELECTROTHERMAL PSEUDO-FLUIDIZED LAYER

2023-09-27T08:26:37+03:00

Hydrogen metallurgy involves the replacement of a carbon reducing agent with a hydrogen one. One of the promising opportunities for the use of hydrogen in metallurgy is the recovery of iron ore pellets that consist of iron oxides. However, there is a problem of heating the hydrogen-containing gas to the recovery temperature. One of the possible solutions to this problem is the use of an electrothermal fluidized bed. The purpose of the article was to determine the principle possibility of recovery of iron oxides in the form of iron ore pellets by high-temperature hydrogen-containing gas in an electrothermal fluidized bed. The authors considered the generation of hydrogen by pyrolysis of natural gas. Conducted thermodynamic calculations of the process of reduction of iron oxides with the obtained hydrogen indicate the optimal temperature range of the process: 900 ... 1500 K. To study this process, a laboratory installation with an electrothermal fluidized bed with a combined heating method was created. This installation is divided into two reaction zones. In the first, natural gas is decomposed into hydrogen and pyrocarbon. Carbon dioxide, which is a valuable material, remains in the first reaction zone. The formed hydrogen with a high temperature enters the second reaction zone where it restores the iron ore pellets. During the process of recovery of iron pellets with high-temperature hydrogen-containing gas, no flame accompanying the process of hydrogen formation by pyrolysis of hydrocarbons was detected. The release of water vapor at the reactor outlet was observed. This means that the hydrogen produced reacted with the iron pellets and reduced them to pure iron. The surface microstructure of the original iron pellet is darker and matte, while the surface microstructure of the processed iron pellet has a lighter color and a shiny surface, which is characteristic of pure metals. This additionally indicates the fundamental possibility of restoring iron pellets to pure iron with high-temperature hydrogen produced by pyrolysis of natural gas in an electrothermal fluidized bed. Research results can be applied in the energy sector, the transport sector, in particular, in the operation of space vehicles. The results of the article can be applied in practice by energy engineers, expert chemists, as well as scientists involved in the development of the latest technologies for obtaining hydrogen.

COMBINED METHOD OF SURFACE HARDENING OF HIGH-SPEED STEELS

2023-09-27T02:44:55+03:00

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.

RESEARCH OF THE WEAR RESISTANCE OF ELECTRO-SPARK COATINGS UNDER ABRASIVE CONDITIONS

2023-09-27T02:18:47+03:00

The reasons for the destruction of parts of the friction units of aircraft and ground aviation equipment, which are made of iron-based alloys, were analyzed, and it was established that during operation, various processes develop on their working surfaces, namely: abrasive wear, seizure, fretting - corrosion, fatigue wear. The analysis of modern technological methods of surface strengthening of machine parts was carried out, the prospects of electrospark alloying of iron-based alloys were determined. Research on the wear resistance of coatings was carried out using a complex methodology, which includes metallographic, electron microscopic, durometric, and other methods of analysis of physical and mechanical methods. The influence of electrode materials on the wear resistance of ESD coatings has been established. Practical recommendations for surface strengthening of parts of automatic transmission systems operating under conditions of abrasive wear are indicated.

EROSIONAL WEAR OF THE LOAD CARRYING CANVAS OF BURNING MACHINES UNDER THE INFLUENCE IRON ORE PELLETS

2023-09-27T01:54:33+03:00

The load-carrying belt of conveyor machines for clods of iron ore concentrate operates in a complex, aggressive dust and gas environment and cyclic "heating-cooling" modes. At the same time, the constituent elements of the load-bearing fabric - gratings also work under the influence of shock and abrasive loads, which leads to their intensive wear, as well as an increase in the regulated working gaps between adjacent gratings, and, therefore, to their premature replacement. In order to predict the degree of wear of the working surfaces of parts (grills), numerical models have been developed at the micro, macro, and meso levels. These models work in various combinations, but in the given conditions of operation of burning machines, due to the specifics of their work, meso- and micro-models rarely appear. The results of the analysis of the defects of the grates, which have failed, indicate the manifestation of macro-models, the schematization of which takes place mainly in the form of an erosive wear model. On the basis of macro models, Bitter's dependences were modified to calculate the degree of erosive wear of grates, and it was also established that to significantly reduce the degree of wear of pallets, it is recommended to use drum-type loading devices that ensure unloading of material with an angle of attack α=35÷45°. At the same time, the best recommended material for grates is steel 30Х14Г8Ю2Л.

DEFINING TESTS OF HEAT-RESISTANT YTTRIUM-CONTAINING SEALING COATINGS FOR HIGH-TEMPERATURE GAS-EROSION RESISTANCE

2023-09-27T01:35:16+03:00

This article describes the testing of heat-resistant yttrium-containing sealing coatings for high-temperature gas-erosion resistance. The study includes careful visualization and characterization of the geometry of the cut-in profile, observation of changes in surface color, and analysis of the internal structure of powder coatings. The first important conclusion is that there are no obvious changes in the geometry of the flute profile and the configuration of the edges, bottom and sides. This indicates the absence of significant mechanical wear of the surface of the coating materials under the influence of high-temperature gas flow. Further analysis suggests that the modeled mechanical pressure and velocity of the flare jet were not large enough to cause destruction of the coating surfaces. A noticeable change in the color of the surfaces was noted. This phenomenon may be the result of the formation of oxides on the surface of materials under the influence of elevated temperature. The exact chemical composition and nature of these oxides require further research to fully understand. Studies indicate the presence of deformation of the internal structure of powder coatings, as well as the accumulation of zones with high and low microstresses. These phenomena indicate the possibility of micro-wear of the coating materials and the formation of additional cohesive bonds. it was found that the yttrium content affects the rate of mass gain of coatings. The weight gain depends on the yttrium concentration and the method of coating application. This relation can have important practical applications in the development of tribological materials with improved properties.

ELECTION OF GEAR OILS BY PHYSICO-CHEMICAL CHARACTERISTICS

2023-09-27T01:09:41+03:00

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.

ANALYSIS OF MODELS AND METHODS FOR ASSESSING THE STRENGTH CHARACTERISTICS OF POLYMER COMPOSITE MATERIALS

2023-09-27T00:04:40+03:00

The expediency of combining complex design systems and conducting standardized mechanical tests in the development of new composite materials in order to increase the reliability of products and structures is substantiated. The analysis of modern software complexes of finite element analysis SolidWorks, ANSYS, Abaqus and Patran/Nastran for modeling the properties of composite materials was carried out. The peculiarities of predicting various forms of destruction of polymer composite materials are determined, estimates of potential mechanisms of destruction, PCM damage models depending on the software complex used in the design of products from composite materials are given. The application of the edge effects model in layered composites, displacement compatibility models, adhesion models, linearized three-dimensional fracture criteria and other fracture models with the rate of energy release, the method of virtual crack closure in calculating the damage resistance of laminated composite structures at the design stages is considered. The main aspects of methods of research and determination of mechanical properties of composite materials under tension and compression according to ISO and ASTM standards are considered. The procedure for creating a regulatory and technical base in the field of production and application of PCM is analyzed from the standpoint of bringing the national standardization system closer to international and European norms and rules.

RELATIONSHIP OF WEAR-FRICTION PROPERTIES AND ENERGY-LOAD OF FRICTION COUPLES OF BRAKE DEVICES

2023-09-26T23:13:34+03:00

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 (I_n) of the maximum surface temperature ( ) on discrete contacts of friction pairs is shown. Graphical dependences of the form f=f(p_a, )and I_n =I(p_a, ), λ = λ( ), а = а( ) and НВ = НВ( ) were analyzed (p_a – 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.

INTEGRAL ASSESSMENT OF THE RISKS OF THE EMERGENCY OF EMERGENCY SITUATIONS IN MARINE CARGO TRANSPORTATION

2023-06-07T18:44:09+03:00

The work provides a methodology for calculating risks based on the use of a model of the safety of cargo transportation by various types, including sea, transport, and a general model of the emergency development scenario. The considered theory of statistical decisions is intended for the development of recommendations on the rational application of actions in conditions of uncertainty and associated risk.

Given that accidents and the risk of emergency situations have a pronounced random nature, the methods of probability theory and mathematical statistics are used to assess risks. Therefore, the article deals with the issue of vehicle accidents and related cases of cargo loss/damage, which are rare events distributed according to the Poisson law. Predicted estimates of the probability of failure of technical means can be determined using the theory of Markov processes.

The practical use of the integrated risk assessment methodology allows already at the stage of the initial design of transport and technological schemes of sea freight transportation to evaluate alternative options according to risk criteria and to develop measures to reduce the level of risk in order to increase the safety of transportation and preserve cargo. At the same time, risks are assessed not only under normal conditions of transportation, but also in cases of accidents, which is a mandatory condition when choosing methods and means to minimize losses and negative consequences of accidents and disasters.

The results of research on the development, development and improvement of the methodology of integrated risk assessment and ways of managing them in emergency situations to increase the safety of sea cargo transportation are also given.

INFLUENCE OF GAS THERMAL PROCESS PARAMETERS SPRAYING OF COATINGS FOR THEIR WEAR RESISTANCE AND ADHESION STRENGTH

2023-06-07T18:09:00+03:00

On principle of equivalent tensions of adhesive connection, the estimation of remaining tensions is conducted in coverage. For this purpose, graphic differentiation of experimental dependence of adhesive durability is utilized from the thickness of coverage. Functional connection is set between adhesive durability, thickness of coverage, critical deformation of basis and remaining tensions. It allows choosing the parameter When using electrical contact treatment after gas-thermal spraying of coatings, positive results were obtained: the value of residual stresses does not exceed 200 MPa; parts with gas-thermal coatings that have undergone electrocontact treatment are characterized by a smooth change in hardness from the coating to the surface of the part and an increased diffusion zones of the system «basis-coverage» at finish treatment and exploitation. the amount of pressure and the technological scheme of the electrical contact treatment process significantly affect the level of residual stresses and the adhesion strength of the coatings. From this point of view, preference should be given to the application of coatings by gas-thermal spraying with subsequent electrical contact treatment with a gradual increase in temperature and pressure of the process.

The method of graphic differentiation of the experimental dependence of the adhesive strength on the thickness of the coating was used to determine the residual stresses in the coatings obtained by gas-thermal spraying with subsequent electrical contact treatment. According to the principle of equivalence of residual stresses and critical deformation of the part during peeling of the coating, a functional relationship of adhesive strength, thickness of the coating, critical deformation of the part and residual stresses was established. This dependence allows you to determine the characteristics of coated parts for their operating conditions.

INFLUENCE OF HEAT TREATMENT ON TRIBOTECHNICAL PROPERTIES OF EUTECTIC ELECTROSPARK COATING

2023-06-07T12:59:41+03:00

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.

THE EFFECT OF FRICTION MODIFIERS ON THE PERFORMANCE CHARACTERISTICS OF LUBRICANTS

2023-06-07T10:04:19+03:00

The analysis of antifriction and antiwear additives to lubricants has been carried out and the mechanisms of formation of protective films on tribocombination elements have been considered. An increase in the antifriction and antiwear characteristics of lubricants due to their additional modification with graphite, molybdenum disulfide, fullerenes, nanotubes or a repair composition has been established. The mechanism for increasing the efficiency of lubricants with friction modifiers is to create a protective surface layer in the process of tribosystem self-organization during friction. It has been established that by empirical analysis it is possible to choose the optimal concentration of the repair and restoration compound RVS, the addition of which to the gear oil provides an increase wear resistance of steel under rolling conditions with slippage. Reducing the wear of contact surfaces is facilitated by mechanical chemical processes that manifest themselves during structural adaptability of finely dispersed components of the geomodifier friction RVS, boundary lubricating films and metal surface layers at friction under dynamic loading conditions. For the main indicators providing an increase in the wear resistance of friction pairs are microhardness of metal surface layers and its gradient depth distribution, microgeometry of the surface layer, formed during friction, and the formation of boundary lubricating layers on friction-activated contact surfaces. These processes are a manifestation of structural adaptability structural materials under study, the consequence of which is qualitative and quantitative change in the microgeometry of surfaces friction. Fullerenes and nanotubes are elementary objects of nanotechnologies, on the basis of any possible macro-objects, which may be of practical importance, - materials and outbuildings. The potential of using these structures (especially nanotubes) exceeds potential of other nanostructures.

THE FATIGUE STRENGTH INVESTIGATION OF STRUCTURAL MATERIALS UNDER THE ASYMMETRIC CYCLIC LOADING CONDITIONS

2023-06-07T08:18:55+03:00

There were analyzed the standard methods of testing the fatigue strength of structural materials samples under asymmetric cyclic loading conditions. It’s shown that fatigue tests of structural materials are time-consuming and long-term. The results of the research can be used to develop a standard for fatigue testing methods of structural materials samples under asymmetric cyclic loading conditions, which will significantly reduce the amount of experiments required to determine the fatigue resistance characteristics under asymmetric cyclic loading.

THERMO-MECHANICAL PHENOMENA IN THE SURFACE LAYERS OF CONTACTING PARTS DURING FRICTION AND WEAR

2023-06-07T00:36:57+03:00

Despite a significant number of theories of friction and wear, the issue of wave formation on contacting surfaces and in the zone ahead of the moving part has not yet received a sufficiently deep justification. Based on accumulated theoretical and experimental data, it is generally accepted to consider the groups of theories: 1) geometric, 2) molecular (adhesive), 3) deformation, 4) combined [1]. The most widespread opinion is that friction is caused by plastic extrusion of the material and the destruction of welding bridges (F. R. Bowden and D. Tabor), which is also confirmed by the hypothesis of Ernst and Margent, where friction is caused by adhesion (at the molecular level and surface roughness). At the same time, the experimental results of F. R. Bowden and D. Tabor indicate that the effect of friction depends on both the adhesion forces and the deformation of the material in the thin surface layer. As a result of the application of significant compressive forces and tangential frictional forces, a large amount of energy is released at the contact of two bodies, and with weak heat exchange with the environment, high gradients of temperature changes occur, and in the case of metal parts, under certain conditions, the welding effect of both individual micro-uniformities and contact surfaces in general, which is confirmed by research results [2].

TRIBOMETRIC TESTING MACHINE FOR INVESTIGATING TRIBOLOGICAL CHARACTERISTICS OF POLYMERS

2023-06-07T00:09:25+03:00

Analysis of methods and installations for assessment of wear and research of tribometric parameters of various materials was carried out. The purpose of the work is to create a tribometric machine and a method of testing the anti-friction and anti-wear properties of polymers and composite materials. That includestemperature registration in frictional contact and in the near-surface layers of triboelements. The main structural diagram of the installation of the tribometric machine, developed at the National Aviation University, is presented. The main characteristics of the installation, the method of testing samples and the parameters of work related to the relevant research of polymer materials and composites based on them are provided. The standardized method specified in ISO 7148-2:2012 is used when testing materials. The proposed elliptical contact form of the triboelements ensures the constancy of the contact load during the experiment. The installation is equipped with a sensor system that allows you to control the speed of rotation and the moment of friction. The rotation speed is measured using a Hall sensor. The system of thermoresistive sensors provides monitoring of environmental conditions and temperature of testing objects. The developed installation can be used for express testing of materials for tribotechnical purposes, which provides an opportunity to develop more effective tribological solutions regarding the structural adjustment of tribo-coupling elements.

DETERMINATION OF SLIDING FRICTION LOSSES IN A GEAR PAIR

2023-06-06T20:27:00+03:00

Increasing the performance of gear drives of machines is an urgent task, so to estimate the total losses in engagement, it is worth considering all components of losses. To solve this problem, the article proposes a method for determining the sliding friction losses in a gear pair. At present, the effect of sliding in the tooth's direction contact line on the friction coefficient and lubrication conditions has not been studied sufficiently. There are two groups of semi-analytical models in the published works. The first group of authors studied the efficiency of spur gears, assuming that the friction coefficient is constant along the entire contact surface of the friction surfaces in any position of the gears during their rotation. The second group of semi-analytical models can be considered as an improvement of the models of the first group with a constant friction coefficient. The accuracy of the empirical formulas used in them limited the accuracy of the description using these models. These empirical formulas are not general and are often a function of certain types of lubricant, available temperatures, speed and load limits, and surface fineness of the test specimens. The coefficient of sliding friction depends on the speed of the mating teeth and the properties of the lubricant; it can also consider such factors as the values of the normal load, the roughness of the tooth surfaces, and the radii of curvature of the tooth profiles. The dependencies have been got to determine the work consumed by friction along the entire meshing line, considering the friction coefficients in the tooth pair for single and double meshing. In this case, the friction coefficient in the gear transmission can be variable by the speed of the mating surfaces, but is the same for two-pair and single-pair meshing. Analytical dependencies have been obtained that make it possible to calculate power losses because of sliding friction depending on kinematic, force, and strength factors, properties of lubricants and gear materials.

THE PHYSICAL PROCESSES AT SUPERCONDUCTIVITY IN PAIRS OF FRICTION BRAKES

2023-06-06T19:56:47+03:00

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.

INFLUENCE OF OXIDATION DEGREE ON ANTIWEAR PROPERTIES AVIATION OILS

2023-06-06T09:27:10+03:00

Control of the quality of lubricants both in product batches and in the process of operation is an important stage in the maintenance of aviation equipment since the assessment of the physicochemical composition of lubricants and their tribotechnical parameters allows for determining the correct oil and lubricant replacement interval. An analysis of the influence of the intensity of oxidation of aviation oil for axial hinges of helicopter propeller bushings on oil's anti-wear characteristics was made. An increase in temperature to 120 ºC leads to the intensification of oxidation processes. The consequences of oxidation are the increased viscosity of oils due to the polymerization of molecules of the oxidized base of lubricants, the formation of organic acids, lacquer and deposits, as well as the exhaustion of most oil additives. An increase in the kinematic viscosity of aviation oils with a duration of oxidation of 96 hours by 0.7...2.12 mm2/s was established, depending on the package of multifunctional additives to the basic base. The assessment of the increase in the acid number of aviation oils and the formation of resins during the determination of stability against oxidation was made - with a duration of oxidation of 96 hours, the rate of formation of oxidation products depends on the package of multifunctional additives. The change in the micro hardness of the metal surface layers at the increase in the oil acid number was analysed and the weakening mechanisms were determined. The growth of steel wear due to the weakening of the metal surface layers due to the plasticizing effect of oxidation products that are formed during thermomechanical activation in the friction process has been established. During friction, the activated surface of the metal acts as an oxidation catalyst. It is justified to reduce the periodicity of lubricant material quality control during operation, which will ensure increased wear resistance of elements of triboconjugation.

MICROORGANISMS - A SOURCE OF BIOLOGICAL CONTAMINATION OF FUELS AND LUBRICANTS IN STORAGE TANKS

2023-03-01T21:26:46+02:00

It has been found that the presence of biological contaminants in tanks, such as corrosion products, microorganisms of various origins, resinous deposits of fuels and lubricants (F&L), can lead to their destruction and a decrease in the condition of F&L, which negatively affects the safety of aircraft flights and the operation of special vehicles. Yeast-like fungi and bacteria were isolated and identified from samples of aircraft TS-1 and diesel fuel: the substrate-specific gassing fungus Hormoconis resinae (Cladosporium resinae) and bacterial cultures of both Gram-positive (G+), Gram-negative (G-) and G-variable "associations". It was found that these microorganisms are able to grow in the presence of F&L, forming powerful colonies of motile and non-motile rod-shaped bacteria. Based on the analysis of the data obtained, it is assumed that in the detected biological contamination of F&L, microorganisms can coexist only in the composition of biofilms. This assumption needs to be further investigated, as does the claim that the adhesion ability of F&L is an important step in the process of their utilization by microorganisms.

THE PROJECT OF FURNACE FOR INDUSTRIAL WASTES DISPOSAL

2023-03-01T21:00:13+02:00

The article describes the real existing project of the furnace performed on the facilities of the Secret-Service metal works company located in the Kyiv Region. It was ordered by a local waste disposal company that imports RDF and accepts garbage from the vicinity and produces RDF by itself as well. The purpose of this article is to show the opportunities of application of the quite simply designed furnace for the purposes of wastes disposal either on enterprises or within a range of an average town. The current project was implemented in reality, allowing getting rid of industrial and household garbage within the ecologic laws of the Ukraine, including the disposal of plastics, rubber, packages, etc. The proposed example of successful pyrolysis technology application in the furnace can be a good basis for further research dedicated to the creation of more advanced furnaces’ types and also to the creation of the additional afterburner furnace.

INFLUENCE OF GAS THERMAL PROCESS PARAMETERS SPRAYING OF COATINGS FOR THEIR WEAR RESISTANCE AND ADHESION STRENGTH

2023-03-01T17:12:36+02:00

The article presents a comprehensive impact assessment based on experimental research technological parameters of the gas-thermal spraying process (spraying distance), design parameters (coating thickness) and operational parameters (conditions operation - load and sliding speed) on grip strength and intensity wear and tear of gas-thermal coatings. the effect of each of them on the properties was established received coatings. The study of HTN coatings with variation of its main parameters made it possible to assess the influence of each of them on the properties of surfaces with sprayed coatings. On the basis of the obtained experimental results, models have been developed that relate the adhesion strength and wear intensity of the coatings to their thickness and spraying distance. Solving the problems of mathematical modeling and optimization of the HTN coating process makes it possible to obtain a comprehensive assessment of the influence of input variables (HTN process parameters) on the output indicators - the properties of sprayed coatings. Analyzing the obtained models, it should be noted that the adhesion strength of the coatings depends on their thickness and spraying distance. The wear resistance of the coatings is influenced by its operating conditions (load and sliding speed). It was concluded that to increase the adhesion strength of gas thermal coatings and reducing the intensity of their wear is expedient to use comprehensively influence of spraying distance, coating thickness and conditions of its operation.

DESTRUCTION OF BRAKE PADS FRICTION MATERIALS

2023-03-01T16:36:42+02:00

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, low-performance, 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.

THE DEFORMATION ASPECT OF SHOCK-WAVE NATURE OF FRICTION AND WEAR

2023-03-01T00:32:33+02:00

As statistical analysis shows, the main reason for the failure of machines is not their destruction, but the wear of moving joints and working bodies under the influence of frictional forces. However, when creating machines, the movable joint is practically not calculated in terms of resistance to wear. At the same time, there are the following methods of tribotechnical calculation, and they are based on the following groups of theories: geometric; molecular, deformation and combined. All these theories consider processes occurring at contact surfaces. In addition, the currently used approach does not take into account the peculiarities of the deformation processes occurring in front of the mobile part. At the same time, the mobile part (stamp) «accelerates» the wave of deformation of the «launch» on the fixed part, which, as a rule, is not taken into account when considering the processes of friction and wear. We note that these deformation processes during friction and wear are due to shear deformations in front of the moving stamp, and despite established ideas, the hypothesis of flat sections is distorted, as a result of which deformation waves appear on the outer surfaces of the half-spaces. In other words, the displaced layers are not able to move freely along the shear plane, while the so-called «confined shear» occurs, which leads to the deplaning of the outer and inner planar sections. With this view of the matter, the surface layer of the half-space either loses its longitudinal stability or is subjected to cyclic stresses. In both cases, wear and intense scratching of the contact surfaces occurs. In addition, with the interaction of the die (or micro-irregularities formed on it) with the micro-irregularities of the strip in both interacting parts, a continuous wave process is established. Note that with an increase in the die speed V, the dynamic coefficient of the system changes in proportion to the change in the die speed. The research made it possible to establish that for the stable operation of the surface layers of the beam-strip it is necessary that the value of the longitudinal (critical) force overload coefficient is less than the number of half-waves of deformation formed in front of the moving die. In addition, it was established that the deformation-wave processes that occur in front of the moving die lead to the formation of permanent plastic or elastic ridges, which are obstacles for the moving die, and these obstacles are interpreted in the differential equations of motion as impulse loads. The obtained results indicate that elements of both the deformation-wave and shock-wave theories of friction and wear are manifested during the interaction of moving parts. The application of the specified approach makes it possible to clarify the calculation methods for friction and wear both in the case of deformation and in the case of geometric micro-uniformities.

INFLUENCE OF ALLOYING THE METAL MATRIX ON THE ANTI-FRICTION PROPERTIES OF EUTECTIC COATINGS

2023-02-28T21:54:43+02:00

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.

ANALYSIS OF POLYMER COMPOSITE MATERIALS FOR SLIDING BEARINGS

2023-02-28T21:32:34+02:00

The mechanical and tribotechnical characteristics of polymer materials are analyzed and the possibility of their improvement by adding reinforcing substances is shown. For Teflon-based composite materials, no change in antifriction properties has been established under lubrication conditions, compared to friction conditions without lubrication, the friction coefficient is reduced by only 1-3%. Effective fillers of polymer materials include carbon fibers, MoS2. , graphite, graphene, SiO2, etc. It was analyzed that the addition of silicon carbide to polyvinyl chloride increases the anti-friction characteristics, heat resistance and dielectric properties of the polymer. Antifriction materials based on polyvinyl chloride have a relatively low coefficient of friction, but it can be improved if silicon carbide is dispersed on the surface of the polymer. It is substantiated that knowledge of the mechanical and tribotechnical characteristics of interacting tribomaterials is necessary for their selection from the point of view of the safety and efficiency of sliding bearings in the machine-building industry.