Journal articles on the topic 'Finishing antifriction non-abrasive treatment'
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1
Shepelenk, IV, VV Cherkun, and A. Warouma. "Improvement of finishing antifriction treatment without abrasive of the rubbing parts surfaces of agricultural machineries." International Journal of Agricultural Research, Innovation and Technology 4, no. 1 (December 3, 2014): 98–101. http://dx.doi.org/10.3329/ijarit.v4i1.21101.
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The wear of machines and mechanisms after rubbing is a major concern. The costs of manufacturing and restoration parts for agricultural machinery are enormous such as the trunnions pinions of hydraulic pumps. Finishing treatment antifriction without abrasive (FTAA) is the existing method of manufacturing and restoration, but it has disadvantages like low work efficiency and the frequent replacement of the instrument. That is why a new method of FTAA parts type ''tree'' has been developed called vibratory finishing treatment antifriction without abrasive, (VFTAA) method. The study was conducted at the laboratory of the State Technical University of Kirovograd (Ukraine) where turn 16K20, the profilograph-profilometer "Talysurf-5", the scanning electron microscope REM-106I, friction machine MI-1M and the stand KI-28097-02M were used respectively for machining, study of micro relief before and after the VFTAA, microstructure, wear resistance and the determination of the break-in period of parts. The results showed that the VFTAA helped reduce the roughness Ra of the samples studied by half compared to the samples processed by polishing and 1.3 times compared to those treated with the FTAA, the break-in period has been reduced four times , this leads to an increase in the life of the hydraulic pump. This technology can be recommended for manufacturing and repair of hydraulic units of agricultural machineries. DOI: http://dx.doi.org/10.3329/ijarit.v4i1.21101 Int. J. Agril. Res. Innov. & Tech. 4 (1): 98-101, June, 2014
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Ipatov, Aleksey, and Sergey Shmykov. "SYNTHESIS OF ANTIFRICTION COATINGS BY THE FABO METHOD." Tekhnicheskiy servis mashin 1, no. 142 (January 2021): 140–47. http://dx.doi.org/10.22314/2618-8287-2020-59-1-140-147.
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In the paper, the technology of obtaining antifriction coatings by the method of finishing antifriction-free abrasive treatment with the implementation of the wear-free effect is proposed. (Research purpose) The research purpose is in developing an effective technology for obtaining copper coatings on the surface of steel parts of the shaft type to reduce the wear rate in the conditions of oil starvation of machine parts. (Materials and methods) During the study, a laboratory facility for the synthesis of antifriction coatings on the surface of steel parts by the method of finishing antifriction-free abrasive treatment has been developed. Brass of the LS-59-1 brand was used as a material for applying a copper antifriction coating. In order to activate the surface of the part and the surface of the filler material, a technological medium based on a ten percent solution of hydrochloric acid and glycerol was used. Authors determined the composition of the technological environment empirically. The obtained laboratory samples were subjected to tribological studies in comparison with standard antifriction alloys. X-ray diffraction studies were performed to determine the phase composition. (Results and discussion) As a result of X-ray diffraction studies of laboratory samples, the presence of iron and copper components in the synthesized coating was studied. The content of oxides on the surface of the coating is insignificant, the internal structure is dense with no visible porosity. The coating consists of 95 percent copper, the synthesis process takes place without oxidation, which gives the coating a high adhesive and cohesive strength. The coating thickness is uniform and varies within 3-5 micrometers. (Conclusions) Comparative tribological studies have shown high resistance to wear and to the setting of the contact surfaces under conditions of oil starvation. The coefficient of friction is stable and low and is in the range of 0.08-0.15. The developed technology makes it possible to increase the wear resistance of steel parts of the shaft type in the shortest possible time and with minimal material costs and can be successfully implemented in the conditions of repair enterprises.
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Ipatov, Aleksey G., and Sergey N. Shmykov. "SYNTHESIS OF ANTIFRICTION COATINGS BY THE FABO METHOD." Tekhnicheskiy servis mashin 1, no. 142 (March 2021): 140–47. http://dx.doi.org/10.22314/2618-8287-2021-59-1-140-147.
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In the paper, the technology of obtaining antifriction coatings by the method of finishing antifriction-free abrasive treatment with the implementation of the wear-free effect is proposed. (Research purpose) The research purpose is in developing an effective technology for obtaining copper coatings on the surface of steel parts of the shaft type to reduce the wear rate in the conditions of oil starvation of machine parts. (Materials and methods) During the study, a laboratory facility for the synthesis of antifriction coatings on the surface of steel parts by the method of finishing antifriction-free abrasive treatment has been developed. Brass of the LS-59-1 brand was used as a material for applying a copper antifriction coating. In order to activate the surface of the part and the surface of the filler material, a technological medium based on a ten percent solution of hydrochloric acid and glycerol was used. Authors determined the composition of the technological environment empirically. The obtained laboratory samples were subjected to tribological studies in comparison with standard antifriction alloys. X-ray diffraction studies were performed to determine the phase composition. (Results and discussion) As a result of X-ray diffraction studies of laboratory samples, the presence of iron and copper components in the synthesized coating was studied. The content of oxides on the surface of the coating is insignificant, the internal structure is dense with no visible porosity. The coating consists of 95 percent copper, the synthesis process takes place without oxidation, which gives the coating a high adhesive and cohesive strength. The coating thickness is uniform and varies within 3-5 micrometers. (Conclusions) Comparative tribological studies have shown high resistance to wear and to the setting of the contact surfaces under conditions of oil starvation. The coefficient of friction is stable and low and is in the range of 0.08-0.15. The developed technology makes it possible to increase the wear resistance of steel parts of the shaft type in the shortest possible time and with minimal material costs and can be successfully implemented in the conditions of repair enterprises.
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Tarasenko, Boris, Evgeny Shapiro, Sergey Voinash, Alexey Kamenchukov, and Аbdul Мudalif Dzhasheev. "Improvement of the Method for Restoring the Bearing Supports of Steel Crankshaft." Materials Science Forum 1031 (May 2021): 50–57. http://dx.doi.org/10.4028/www.scientific.net/msf.1031.50.
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In the science of car repair, the problem of restoring worn-out crankshafts is very relevant. The engineering solutions proposed in the article will provide an increase in the technical and economic indicators of repair: an increase in the quality of coating by a gas-flame method with a finishing non-abrasive antifriction treatment. At the same time, the engineering solution consisting in the formation of one groove on each journal of the crankshaft, brazing of a copper wire, followed by flame spraying of a coating, sealed by a disk, and grinding of the journals (the bearing supports), provides a non-wear effect. So, thanks to the coil of copper wire, the resource of the crankshaft increases and the cost of repaired crankshafts are reduced in comparison with new ones.
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Shepelenko, I. "Technological factors influence on the antifriction coatings quality." Problems of tribology 100, no. 2 (June 23, 2021): 50–57. http://dx.doi.org/10.31891/2079-1372-2021-100-2-50-57.
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The conditions for the antifriction coatings formation during finishing antifriction non-abrasive treatment (FANT) are analyzed. The requirements for this kind of coatings and the main criteria for assessing their quality are noted. A relationship has been established between the quality of the coating obtained with FANT and the technological factors that determine the conditions for contacting the tool with the treated surface. It is proved that the shape and size of microroughnesses of the treated surface determine the efficiency of the microcutting process and filling the microcavities with the rubbed material. Technological factors influence on the coating quality was investigated during FANT by implementing a multifactor experiment, as a result of which a connection was established between the technological parameters of the process (total friction path, load on the tool), as well as the length of the supporting surface with indicators characterizing the coating quality. Statistical models were obtained for mass transfer of antifriction material, area (continuity) of the coating and surface roughness at natural values of the factors, which made it possible to establish the studied factors influence on the optimization parameters. The analysis of the experimental scattering graphs made it possible to clarify the nature of the factors changes and analyze their mutual influence on the optimization criteria. Taking into account the inversely proportional relationship of the optimization criteria, the achievement of their maximum values at the same time is impossible, therefore, the values are taken according to the final result of the FANT process. The range of the studied factors values is established, the regularities of their change are substantiated from the point of view of the selected optimization criteria. Determination the rational values of the FANT process technological parameters will improve the antifriction coatings quality obtained by a friction-mechanical method.
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Nemyrovskyi, Yakiv, Ihor Shepelenko, Ruslan Osin, and Eduard Posviatenko. "IMPROVING THE PROCESSING QUALITY OF CYLINDER LINERS USING COMBINED TECHNOLOGY." Cutting & Tools in Technological System, no. 96 (March 2, 2022): 121–30. http://dx.doi.org/10.20998/2078-7405.2022.96.13.
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Due to the use of surface engineering methods, a combined technology for processing the working surface of internal combustion engines cylinder liners has been developed. The advantages and disadvantages of traditional liners processing technologies are analyzed, which allowed identifying ways to improve them. A new technological process of cylinder liners processing is proposed, which includes operations of deforming broaching and finishing antifriction non-abrasive treatment. The technological equipment and tools for the chosen technological process realization are chosen. Experimental studies of the proposed technical solutions feasibility are carried out. The microrelief of the treated surface, roughness parameters, hardness distribution according to the wall thickness were determined for the studied liners, and the amount of wear was determined for the liners after running-in. Parameters analysis of geometric, mechanical and tribological characteristics of the liners working surface, processed by the existing and proposed technology showed significant advantages of the latter. There is an increase in the productivity of processing part up to 4 times, reducing the cost of the tool up to 3 times, and in general – reducing the cost of restoring the liner. It is proved that the use of the proposed technology allows improving the physical-mechanical characteristics of the working surface: strengthening the surface layer to a depth of 0.3 mm, as well as obtaining a roughness close to the operational.
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Serezhkin, M. A., and E. L. Melnikov. "Development of technology of hardening of large punch matrices." Izvestiya MGTU MAMI 8, no. 1-2 (March 10, 2014): 214–21. http://dx.doi.org/10.17816/2074-0530-67885.
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There was developed a technology to enhance the resilience of large dies and punches. Maximum contact load on the exhaust side of the punch die was measured. The experimental research of non-abrasive finishing antifriction coatings wear resistance was carried out taking into account the influence of lubricants.
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Nguyen, Nam Duc. "Study on the application of non -Newton fluid in curved surface polishing." Science and Technology Development Journal 20, K5 (August 31, 2017): 58–63. http://dx.doi.org/10.32508/stdj.v20ik5.1160.
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Traditionally, the curved surfaces are generated by a complicated machining process to achieve the required surface quality. To simplify this process, the abrasive will be mixed with the binder to become a polishing slurry. This slurry does not obey the Newton laws when it moves. This process will produce the shear stress for the slurry on the machining surface. Based on the non-Newton fluid, the curved surface will be machined by a simple machining process. In this paper, the effects of grinding speed, slurry concentration and abrasive size on the surface roughness are discussed. The experimental results show that the polishing speed has an obvious influence on surface finishing. With the increase of the polishing speed, the surface roughness reduces. In addition, the slurry concentration also affects the surface quality like the polishing speed. The abrasive size has a small effect on the surface finishing. The surface roughness of steel spherical workpiece Ø40 mm is reduced sharply from Ra = 130 nm to Ra = 23 nm after treatment.
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Shepelenko, Ihor, Yuriy Tsekhanov, Yakiv Nemyrovskyi, Eduard Posvyatenko, and Pavlo Eremin. "Simulation of micro-cutting in the process of finishing anti-friction non-abrasive treatment." Ukrainian journal of mechanical engineering and materials science 5, no. 2 (2019): 43–52. http://dx.doi.org/10.23939/ujmems2019.02.043.
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Shepelenko, I. "The study of surface roughness in the process of finishing anti-friction non-abrasive treatment." Problems of Tribology 25, no. 1 (March 26, 2020): 34–40. http://dx.doi.org/10.31891/2079-1372-2020-95-1-34-40.
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Li, Yonggang, Xingfu Wang, Shengqiang Yang, Lifeng Hou, Yinghui Wei, Zhongjie Zhang, and Xiaoni Yang. "Investigation on Wear Behavior of Cryogenically Treated Ti-6Al-4V Titanium Alloy under Dry and Wet Conditions." Materials 12, no. 18 (September 4, 2019): 2850. http://dx.doi.org/10.3390/ma12182850.
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Titanium alloys are widely used in many fields because of their excellent comprehensive properties. However, its poor friction and wear properties limit its many potential applications. In general, the surface roughness of important parts manufactured by titanium alloy should meet certain requirements. As a low-cost and high-efficiency processing method, barrel finishing has been used for the surface finishing of titanium alloys. The main material removal mechanism of barrel finishing is micro-cutting/grinding, which is similar to the material wear mechanism under some conditions. In addition, titanium alloys are subjected to a low force in common surface finishing processes. Cryogenic treatment is a method that can improve the comprehensive properties of titanium alloys. Therefore, the friction and wear behavior of cryogenically treated Ti-6Al-4V titanium alloy (CT Ti alloy) and non-cryogenically treated Ti-6Al-4V titanium alloy (NT Ti alloy) at a low load and scratch speed was studied comparatively in this paper. The results show that the CT Ti alloy exhibits a lower friction coefficient and wear rate under both dry and wet wear conditions. Under wet conditions, the stabilized friction coefficient is lower than that under dry conditions. The stabilized friction coefficient of CT Ti alloy is 0.18 after reaching a stable wear stage under wet conditions. Under dry wear conditions, the NT Ti alloy mainly showed typical abrasive wear, heavy adhesion wear and oxidation wear characters. The wear mechanisms of CT Ti alloy are mainly abrasive wear, slight adhesion wear and oxidation wear. Under wet wear conditions, the wear mechanism of NT Ti alloy is abrasive wear and slight adhesion wear. After cryogenic treatment, the mechanism for CT Ti alloy is slight abrasive wear.
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Li, W. D., Ming Lv, and Sheng Qiang Yang. "Preliminary Research on the Post Treatment of Fluid Magnetic Abrasivetool." Key Engineering Materials 455 (December 2010): 161–64. http://dx.doi.org/10.4028/www.scientific.net/kem.455.161.
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Fluid magnetic abrasivetool(FMA) is one kind of latest finishing abrasivetool which is a sort of suspended fluid composed by magnetic particles, nonmagnetic abrasive particles, surfactants in a non-magnetizable carrier liquid. After a period of working time, the performance-life of the abrasivetool ended because of the cutting- blade of the abrasives particles being passive. While the most costly component- the magnetic particles (carbonyl iron particles) can be reused. This paper has made up two recovery flows to separated carbonyl iron particles from others.
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Bagmutov, V. P., N. G. Dudkina, I. N. Zakharov, M. D. Romanenk, and V. V. Chekunov. "Influence of structure and properties of surface layer on fatigue durability of hardened steels strengthened by combined electromechanical treatment." Izvestiya. Ferrous Metallurgy 62, no. 6 (June 28, 2019): 438–50. http://dx.doi.org/10.17073/0368-0797-2019-6-438-450.
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Using the example of hardened carbon steels (steel 45, U8), the effect of combination of various surface hardening technologies is considered (using electromechanical processing, surface plastic deformation, non-abrasive ultrasonic finishing and their combination) on changes in structural state and surface microhardness, cyclic durability of hardened specimens and fatigue failure mechanisms. The studies were carried out by the methods of optical and scanning electron microscopy and by microhardness and fatigue tests. It is shown that for the investigated steels in quenched state, a high-speed pulsed thermo-deformation effect during electromechanical processing is accompanied by an increase in the surface microhardness (by more than 50 %) and decrease in the fatigue limit (by 20 – 30 %). Such a change in properties is associated with formation in the surface layer of substantially non-equilibrium, inhomogeneous in chemical composition, ultradispersed phases with increased hardness. At the same time, in the near-surface metal volumes tempering processes of the hardened structure proceed with the formation of softening zones and tensile residual stresses, accompanied by a decrease in the microhardness in these zones and the fatigue limit of the specimens. Such effects reduce some of the materials performance characteristics during surface hardening. The ways to improve the properties of such products due to additional technological operations require further studies. Combined surface hardening (based on electromechanical processing, surface plastic deformation and non-abrasive ultrasonic finishing) of carbon steels allows, due to variations in the intensity of temperature and deformation effects, to purposefully change the structural-phase composition and stress-strain state of the surface and near-surface metal layers. As a result, it becomes possible to form a balanced complex of strength and fatigue characteristics of the samples, depending on the preliminary heat treatment of steel. The operations of surface plastic deformation and non-abrasive ultrasonic finishing after electromechanical hardening, due to intensive plastic deformation provide smoothing of the surface and healing of near-surface defects and allow correction of stress-strain state of the processed metal. It provides an increase in microhardness in the tempering zone by 20 – 25 % and the fatigue limit of the samples by 25 – 30 %.
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Smolentsev, E. V., M. V. Kondratev, E. V. Pavlov, and V. V. Kuts. "Non-abrasive Finishing of Mating Surfaces of Machine Parts Using Mixed Techniques with Electromagnetic Fields Application." Proceedings of the Southwest State University 24, no. 3 (December 6, 2020): 51–65. http://dx.doi.org/10.21869/2223-1560-2020-24-3-51-65.
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In various branches of mechanical engineering, faucets, valves, gate valves and other shut-off devices are manufactured and used. Their main purpose is to regulate the flow rate and direction of flows of liquid and gas media. Features of such products in the aerospace and petrochemical engineering are special strict requirements due to the specificity of their operation. These include, for example, high pressure, resistance to aggressive, fire-and explosive environments, leaks of which are unacceptable according to safety rules and environmental legislation. The design of such products, as a rule, assumes high requirements for accuracy and roughness, especially at the interface of parts, high strength in case of impact pulse effects of the fluids in them. To ensure the above characteristics, finishing abrasive treatment is most commonly used, which can result in the effect of impregnation of the surfaces of products, which will negatively affect the useful life and performance indicators of the mating surfaces. At the same time, it is obvious that mechanical finishing without any use of abrasives is extremely difficult and time-consuming. The authors of the article suggest elimination of the negative effect of impregnation by means of mixed machining techniques with the application of electromagnetic fields. Purpose. The purpose of the work is to develop a technology for non-abrasive finishing of machine parts by developing a model that allows selection or calculation of the production modes of gapless mating parts of locking devices applied in various industries. Methods. The method of the research is the use of the scientific basis of mixed machining techniques, the theory of mass transfer in electrical machining, the fundamental foundations of mechanical engineering technology, modern methods for studying characteristics at the final stages of machining, modern measuring tools, special technological equipment, as well as computer technologies. Results. As a result of the research, new technique and devices were developed. This made it possible to implement a non-abrasive finishing operation of the mating surfaces of parts made of metal materials, the processing of which by mechanical methods is difficult. Conclusion. As a result of the conducted research, it became possible to obtain high-quality high-resource gapless locking products and to reduce labor intensity of the finishing operation up to 5 times and preparation for the production up to 2 times.
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Gileta, Viktor, and Anatoly Beznedelnyy. "The mechanism of wearing of the hard alloy tool under ultrasonic reinforcing finishing treatment." MATEC Web of Conferences 224 (2018): 01008. http://dx.doi.org/10.1051/matecconf/201822401008.
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The working capacity of indenters prepared from hard alloy VK8 under conditions of reinforcing finishing treatment by ultrasonic tools was investigated. It was found that under normal treatment conditions, normal wear of the hard alloy takes place. An electron microscopic study of the morphology of the surface of the wear area and its state after the etching of cobalt (Co) using replicas was performed. X-ray microanalysis of the wear area was performed. No obvious traces of adhesive, diffusion, abrasive wear were detected. It was shown that the deterioration of the hard alloy tool VK8 mainly occurs as a result of fatigue failure, which leads in the investigated speed range of the part 10...120 m/min to the precipitation of individual carbide grains and whole groups of them. The non-linear nature of the wear-velocity curve is due to allotropic transformations of cobalt. It was found that at cobalt speeds of 10...50 m/min, the first allotropic transformation from the initial β-Co state to α-Co occurs, and then the second partial allotropic conversion of α-Co to β-Co occurs at a velocity of more than 50 m/min. The presence of a β-Co phase, which is more brittle, leads to an intensification of wear. The WC-WC boundaries and the deformation of WC carbides are not responsible for the formation of the wear surface microrelief and the integral wear of the carbide tool.
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Costa, Cecília Atem Gonçalves de Araújo, Rodrigo Richard da Silveira, José Carlos Pereira, Juliano Sartori Mendonça, and Sérgio Lima Santiago. "Enamel microabrasion: achieving aesthetic success to dental fluorosis in a single session – one-year follow-up." Revista Odonto Ciência 33, no. 1 (December 30, 2018): 121. http://dx.doi.org/10.15448/1980-6523.2018.1.29637.
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OBJECTIVE: To describe the enamel microabrasion technique used to treat the patient with white stains due dental fluorosis, highlighting the importance of complete anamnesis and clinical examination to achieve the clinical success.CASE DESCRIPTION: patient’s complains, aesthetic self-perception, age, general health, history of excessive intake of fluoride and time of teeth development were considered to the diagnosis and treatment plan. Also, dental trans illumination was used to evaluate the white spots diffusion and estimate the lesion’s length. An abrasive paste mixture of equal parts 37% phosphoric acid and pumice was applied with a wooden spatula in order to perform enamel microabrasion. After the last application, the teeth were polished with finishing discs and a neutral sodium fluoride gel was applied to enamel remineralization. Satisfactory results in the aesthetic improvement were possible with a minimally invasive and cost-effective technique. The dental trans illumination after treatment showed the disappearance of the enamel opacities, preserved on the one-year follow-up.CONCLUSION: Cosmetic dentistry has been increasingly practiced today. However, a correct aesthetic planning should be based on current restorative dentistry concept. For any type of procedure, the dentist should opt for sound tooth structure preservation. This technique might be an efficient alternative to restorative treatments and can be considered a successful procedure. In cases of esthetic alterations due fluorosis, non-invasive methods such enamel microabrasion should be considered before invasive restorative treatments.
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Zlamal, Tomas, Ivan Mrkvica, Tomas Szotkowski, and Sarka Malotova. "The Influence of Surface Treatment of PVD Coating on Its Quality and Wear Resistant." Coatings 9, no. 7 (July 13, 2019): 439. http://dx.doi.org/10.3390/coatings9070439.
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The article deals with a determination of the influence of a cutting edge preparation on the quality and wear resistance of coated cutting tools. Cutting inserts made from a sintered carbide with a deposited layer of PVD coating were selected for measurement. Non-homogeneity caused by the creation of droplets arises in the application layer during the process of applying the coating by the PVD method. These droplets make the surface roughness of the PVD coating worse, increase the friction and thereby the thermal load of the cutting tool as well. Also, the droplets could be the cause of the creation and propagation of droplets in the coating and they can cause quick cutting tool wear during machining. Cutting edge preparations were suggested for the improvement of the surface integrity of deposited layers of PVD coating, namely the technology of drag finishing and abrasive jet machining. After their application, the areal surface roughness was measured on the surface of coated cutting inserts, the occurrence of droplets was tracked and the surface structure was explored. A tool-life test of cutting inserts was carried out for verification of the influence of surface treatment on the wear resistance of cutting inserts during the milling process. The cutting inserts with a layer of PVD coatings termed as samples A, B, and C were used for the tool-life test. The first sample, A, represented the coating before the application of cutting edge preparations and samples B and C were after the application of the cutting edge preparation. A carbon steel termed C45 was used for the milling process and cutting conditions were suggested. The visual control of surface of cutting inserts, intensity of wear and occurrence of thermal cracks in deposited PVD layers were the criterion for the evaluation of the individual tests.
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Bagmutov, V. P., V. I. Vodopyanov, I. N. Zakharov, D. S. Denisevich, M. D. Romanenko, and N. G. Nazarov. "Influence of surface hardening by combined thermal force impacts on VT22 titanium alloy fatigue life and damage." Izvestiya Vuzov. Tsvetnaya Metallurgiya (Universities' Proceedings Non-Ferrous Metallurgy), no. 6 (December 16, 2020): 65–75. http://dx.doi.org/10.17073/0021-3438-2020-6-65-75.
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The study covers the influence of electromechanical surface treatment (EMT), non-abrasive ultrasonic finishing (NAUF), their complex influence with subsequent aging on the fatigue life and surface microhardness changes. Samples for research were made of VT22 transition alloy rods after standard thermomechanical treatment. EMT was carried out by sample surface rolling with a roller and applying a high density current between them. As a result, surface thermomechanical treatment was carried out with the local fast surface heating and cooling. NAUF were implemented by shock treatment with an ultrasonic emitter striking on the treated surface. This revealed 1.8 times higher fatigue life when loading by rotational bending (with amplitude of 0.5σв) for samples after NAUF in comparison with the untreated initial state together with a slight increase in microhardness (up to 16 %). EMT reduces microhardness and fatigue life by almost 20 % and 70 %, respectively. EMT + NAUF complex processing has an insignificant effect on microhardness, but it increases fatigue life by 40 % with respect to EMT. Aging at 450 °C for 5 hours increases microhardness after EMT by 30–40 % with a simultaneous increase in fatigue life by 2 times. The aging of samples subjected to EMT + NAUF revealed virtually no increase in microhardness, but increased fatigue life by almost 3 times (as compared to EMT). According to fractography results, the reduction in fatigue life after EMT is associated with a reduction in the crack initiation stage, which virtually excludes this stage of fatigue damage accumulation from the overall sample fatigue life.
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"Electric-Spark Alloying of Metal Surfaces with Graphite." Progress in Physics of Metals 23, no. 1 (March 2022): 27–58. http://dx.doi.org/10.15407/ufm.23.01.027.
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The article reviews and analyses the current scientific research in the field of surface treatment of metal surfaces with concentrated energy fluxes (CEF) — the electric-spark (in the literature, known also as electrospark) alloying (ESA), which makes it possible to obtain surface structures with unique physical, mechanical and tribological properties at the nanoscale. The ESA method with a graphite electrode (electrospark carburizing — EC) is based on the process of diffusion (saturation of the surface layer of a part with carbon), and it is not accompanied by an increase in the size of the part. In this article, the influence of the EC parameters on the quality of the carburized layer is investigated. The microstructural analysis shows that the three characteristic zones could be distinguished in the structure: the carburized (‘white’) layer, the finely dispersed transition zone with fine grain, and the base metal zone. The analysis of the results of the durometric studies of the coatings is carried out. To achieve the required parameters of dimensional accuracy and roughness of the working surface of the part after the EC process, it is necessary to use the method of non-abrasive ultrasonic finishing (NAUF). In addition, because of applying the NAUF method, the surface roughness is decreased, the tensile stresses are changed to the compressive ones, and the fatigue strength is increased too. In addition, to reduce the roughness of the treated surface, it is proposed to apply the EC technology in stages, reducing the energy of the spark discharge at each subsequent stage. In order to increase the quality of the carburized layer obtained by the EC process, it is proposed to use a graphite powder, which is applied to the treated surface before alloying. The comparative analysis shows that, after the traditional EC process at Wp = 4.6 J, the surface roughness of steel 20 is Ra = 8.3–9.0 μm, and after the proposed technology, Ra = 3.2–4.8 μm. In this case, the continuity of the alloyed layer increases up to 100%; there increases the depth of the diffusion zone of carbon up to 80 μm as well as the microhardness of the ‘white’ layer and its thickness, which increase up to 9932 MPa and up to 230 μm, respectively. The local micro-x-ray spectral analysis of the obtained coatings shows that, at the EC process carried out in a traditional way, the applying Wp = 0.9, 2.6, 4.6 J provides the formation of the surface layers with high-carbon content depths of 70, 100, 120 μm, respectively, and with the use of a graphite powder, they are of 80, 120, 170 μm. While deepening, the amount of carbon is decreasing from 0.72–0.86% to the carbon content in the base metal — 0.17–0.24%. In the near-surface layer formed with the use of the new technology, the pores are filled with free graphite, which could be used as a solid lubricant to improve the operating characteristics of the friction-pairs parts processed thereby.