When applying coatings using various methods on the surfaces of moving parts that work in joints, it is important to make sure that the coatings are strong and wear-resistant in order to return them to their original resource. All existing hardening technologies and materials used to perform coatings have their own characteristics, therefore, the quality of the resulting coatings can be judged only after specific tests. (Research purpose) The research purpose is in evaluating the properties of the coating obtained by the method of electric spark hardening, and its ability to resist friction and mechanical wear. (Materials and methods) Authors conducted tests on the basis of the "Nano-Center" center for collective use. A coating was applied on the BIG-4M unit with a VK-8 hard alloy electrode, tribological properties were evaluated on a CSM Instruments TRB-S-DE-0000 tribometer, the width of the friction track was measured after the test using an inverted OLYMPUS gx51 optical microscope, and samples were weighed before and after the test on a VLR-200 analytical balance. Conducted research in accordance with GOST 23.224-86 and RD 50-662-88 guidelines. (Results and discussion) The article presents performed tests on the run-in and wear resistance of the coating. The samples were worked on with a step-by-step increase in the load. During the tests, the friction force was drawed on the diagram. Authors compared the results with the reference sample, an uncoated surface. (Conclusions) The resulting coating has better run-in and wear resistance compared to the standard, and the increase in wear resistance in dry friction conditions is very significant.

Equipment for the production and transportation of bulk agricultural materials operates under extremely difficult operating conditions, is exposed to abrasive particles of the processed material. Such working conditions lead to changes in operational properties, deterioration of the technical condition of the equipment and the occurrence of malfunctions, which are expressed in changes in the original shapes, sizes, weight, structure of the material and mechanical properties. (Research purpose) The research purpose is to predict the performance of composite coatings using a mathematical apparatus that adequately describes the process of abrasive wear of the contact surface of the grain conveyor auger when working with abrasive particles of the processed material. (Materials and methods) As a sample for modeling the process of surface wear, authors chose a screw conveyor, the working screw surface of which is treated with plasma spraying in order to increase its wear resistance. The screw works in an abrasive environment, without touching by the contact surface with other bodies. External abrasive wear is characterized by the presence of scratches or cavities oriented in the direction of sliding. The article presents the model of abrasive wear of the grain conveyor screw and numerical methods of its calculation. (Results and discussion) The article describes a method for assessing the wear resistance of restored shafts by determining the wear intensity of the surface of the part and the energy intensity of linear wear for parts with non-stationary geometry. The article presents a method for calculating the shape and contact area of composite particles with the recovered surface. The obtained expression is valid when ensuring the deviation of the screw speed during the test from the nominal one, not exceeding 10 percent of the set value, the error of applying the load on the screw does not exceed 5 percent. (Conclusions) As a result of the study, the article presents the dependence of the intensity of abrasive wear as a function of the geometry of the surface to be restored and the density of the applied material.

The most important advantages of titanium alloys over other structural materials are their high specific strength and heat resistance, combined with high corrosion resistance and low density. Despite all the positive characteristics of titanium alloys, their tribotechnical properties are very poor, which limits the use of these materials in moving joints. (Research purpose) The research purpose is in increasing the wear resistance and reliability of friction units made of titanium alloys by means of electric spark processing. (Materials and methods) For the study there was used samples of disks with a diameter of 60 and a thickness of 5 millimeters made of a hard alloy of the VT20 brand, an EIO "BIG-1M" installation, a Niton XL3t X-ray fluorescence spectrometer, a Surtronic profilometer, a TRB-S-DE-0000 tribometer, and an OLYMPUS GX51 microscope. (Results and discussion) Coatings were applied to samples made of titanium alloy by electric spark treatment with electrodes made of different materials. The tribotechnical characteristics of such coatings were studied in accordance with the ASTM G99 standard. It was found that the roughness of the samples after electric spark treatment significantly exceeds the roughness of the untreated sample. According to the results of the experiments, the most optimal electrode material was selected to increase the wear resistance of the surfaces of titanium alloys. The titanium alloy after electric spark treatment with a graphite electrode has a high wear resistance and a low coefficient of friction; graphite deposited on the surface of the sample does not form a strong coating, but plays the role of a solid lubricant that is gradually consumed during wear. (Conclusions) The surfaces obtained with the graphite electrode have the best wear resistance and the lowest friction coefficient.

The use of scrap metal and waste solves the problems of preservation of natural resources, reduces energy and economic costs. In mechanical engineering, aluminum bronzes are one of the most popular, they are used in products where such indicators as high strength and ductility, wear resistance and corrosion resistance are needed. (Research purpose) The research purpose is to make a surfacing electrode from scrap copper alloys, to investigate the properties and the coating processes when applying this material. (Materials and methods) The article presents the microstructure and microhardness of the secondary bronze coating and the material for surfacing by the method of electroerosive dispersion of bronze scrap. A compact semi-finished product was created from the resulting powder using spark plasma sintering technology, which was applied to steel samples by electric spark treatment. (Results and discussion) The study of the microhardness of the coatings showed that the coatings made of bronze BrAZh9-4 have a microhardness approximately 1.7-2 times greater than sintered bronze, while the characteristics of the thermal influence zone and its presence directly depend on the substrate material and the electrode material. When getting materials by this method, the elemental composition can be adjusted depending on the required tasks. (Conclusions) The studied material after spark plasma sintering consists of finely dispersed spherical grains, which affects the application parameters and coating characteristics. When applying a coating with the same electrode to different grades of steel, the coating changes with the same parameters of the material application.

Additive technologies become to be widely used in modern mechanical engineering. There are different methods and equipment for carrying out this task, but they all require a starting material - a metal powder with certain physical and chemical characteristics. In modern realities, it is important for Russia to provide itself with high-quality and inexpensive raw materials, which justifies the search for new methods. (Research purpose) The research purpose is considering the most popular and energy-efficient methods of manufacturing metal powder materials for additive manufacturing, justifying the use of a promising method of electroerosive dispersion, which allows obtaining powders with the required characteristics from mechanical engineering waste. (Materials and methods) Literature sources, scientific papers, as well as laboratory equipment were used to study the properties of powder materials, in detail: Olympus GX-51 inverted metallographic microscope, Microtrac Bluewave particle size analyzer, Autosorb-1 specific surface area analyzer, QUANTA 600 FEG electron-ion scanning microscope, drying cabinet SHS-80-01 SPU, a set of sieves according to GOST 2715-75, analytical scales Acculab ALC-210d4. (Results and discussion) Various atomization methods and the properties of metal powders that can be used in additive technologies were analyzed and described. The method of electroerosive dispersion was noted as promising and the powder material obtained with its help was studied. (Conclusions) Additive technologies are becoming more widespread. An urgent task is the search for new ways to obtain metal powders for their producing. The most promising is the method of electroerosive dispersion, which allows obtaining powders with specified properties from mechanical engineering waste. The particles of this powder have a regular rounded shape, high specific surface area and low porosity.