Electric-spark Alloying Research Articles

Increase of durability of cutting elements in forage equipment using electric spark alloying

Features of interaction between the contact surfaces of cutting elements and ground raw materials used for forage preparation determine ways to increase the wear resistance of these elements, which are based on the formation of layers on their working surfaces with physical and mechanical properties and relief corresponding to these features. Because the conditions in the contact zone are variable, selective local application of electrophysical reinforcing coatings can ensure equal strength of different working surfaces or create conditions for self-sharpening of cutting edges and thereby increase their wear resistance. Electric spark alloying is a micro-welding process that uses short-term electrical pulses of high current to deposit the electrode material on a underlay of any electrically conductive metal material. The method of electric spark alloying is based on the phenomenon of metals and alloys erosion under the influence of electric current. The main disadvantage of electric spark alloying is the high roughness of the hardened surface after processing. Received wear-resistant layer should maintain as much thickness as possible and avoid further mechanical treatment of the surface that increase the durability of the restored part and reduce the total cost of work on reinforcement.

XRD study of the surface of aluminum alloy AK5M7 after electric-spark alloying

XRD study of the surface of aluminum alloy AK5M7 after electric-spark alloying

Electric Spark Alloying of Radiant Coils for Pyrolysis Furnaces

Currently, the petrochemical industry uses furnaces to produce ethylene, the main element of which is radiant coils designed for the decomposition of straight-run gasoline into pyrolysis gas, which is the main product for producing ethylene. In radiant coils, the gasoline decomposition process must take place at a temperature of about 800 °C with a high heating rate in order to avoid coking of the coils. Heat is supplied by radiation from the inner lining of the furnaces heated by the flame of flat-flame gas burners. For radiant heat transfer to occur, the surface of the coils must have a high degree of blackness. This article presents the developed technology for coating heating surfaces with shungite and the results of increasing their emissivity to intensify radiant heat transfer. Measurements of the emissivity after electrospark alloying were carried out by the radiation method, according to which, according to Kirchhoff’s law, the emissivity is equal to the emissivity at equal temperatures.

New technological methods of protecting the sur-faces of the parts of transport and lifting machines against fretting corrosion

Damage to the surfaces of parts of transport and lifting machines from fretting wear is accompanied by the emergence of stress concentrators, changes in the mechanical properties of structural elements, weakening of tension and other phenomena, which leads to the destruction of individual structural elements and can cause serious accidents. Thus, the study of the problems of fretting wear, the study of the causes of its occurrence and the development of methods to increase fretting resistance is an urgent task that requires timely solution. Goal. The purpose of the work is to increase the reliability and durability of parts of transport and lifting machines by increasing the fretting resistance of joints by forming special coatings on the contact surfaces of the connecting parts. Methodology. Both analytical methods of research and experimental check of efficiency of the offered methods of increasing resistance against fretting wear of parts’ surfaces were used. Results. A study of the influence of various factors on the intensity and features of fretting processes on the contact surfaces of various parts of transport and lifting machines, substantiated the use of methods of electric spark alloying, epilation, metal plating of surfaces subjected to fretting wear. Originality. A new method of manufacturing a fixed joint type "Shaft - hub" of steel parts is offered, which provides the increased fatigue strength of the shafts in fixed joints and recommendations are developed for the materials used and processing modes. A new method of protecting the parts of the elastic coupling from fretting corrosion is proposed, in which a chemical and physical effect is performed on the surface layer of the parts in contact with friction pairs. A new method is offered for protecting flexible elements of elastic couplings from fretting corrosion and increasing their durability in more severe operating conditions, by changing the quality parameters of their surface layers by applying corrosion-resistant lubricants. Practical value. The use of the proposed technological methods provides a significant increase in resistance to fretting wear of the parts’ surfaces, which is confirmed by the results of the bench tests.

МЕТОДОЛОГИЧЕСКИЕ АСПЕКТЫ ПРИМЕНЕНИЯ ЭЛЕКТРОИСКРОВОГО ЛЕГИРОВАНИЯ. ЧАСТЬ 2: РАЗРАБОТКА МЕТОДОЛОГИИ ИССЛЕДОВАНИЯ, КРИТЕРИЕВ И ПОКАЗАТЕЛЕЙ ЭФФЕКТИВНОСТИ

There is no systematic information in the literature about the methodology for achieving the required functional properties of the executive surfaces of various objects: machine parts, tools and technological equipment for mechanical processing of materials in cold and hot conditions. (Research purpose) The research purpose is in developing a methodology for creating executive surfaces of parts for various purposes using electric spark alloying and justifying the criteria and parameters for evaluating this method. (Materials and methods) The authors created a methodological base by using the deductive method with gradual level specification and addition of the developed topics. The basis of the development was the four-link paradigm of G. V. Samsonov “composition-technology-structure-properties”, supplemented by a feature of the functional purpose of the material and extended features of the composition and technology. Authors used a hypothetical-deductive model for obtaining scientific knowledge to develop a methodology for creating executive surfaces of parts using the ESA method. (Results and discussion) The article shows the role of hardness, melting temperature, and elastic modulus of materials in the formation of electric spark coatings and their properties, identifies technological variants of the doped layer macrostructure, reveals the wettability of the anode material with the cathode material, the mutual solubility of the materials of the "anode-cathode-medium" system, and their chemical affinity. (Conclusions) The article presents the methodological schemes for the study and selection of the anode material, which largely determines the desired properties of the doped layer. Authors proposed a methodological approach to the development of criteria and indicators for the effectiveness of electric spark alloying, analysis and generalization of the main methodological provisions for strengthening and restoring the executive surfaces by this method, taking into account their functional purpose. The article considers a number of dominant factors that affect the efficiency of electrospark doping, as well as the selection and development of performance criteria in the field of surface materialology.

Nanostructuring of the surface layer by the method of electric-spark alloying

The creation of a universal, economical and high-tech way of increasing the life of both worn and new parts has become an urgent task. Such methods include nanostructuring of surface coatings, which can be performed by electric spark alloying. (Research purpose) The research purpose is studying the possibilities of electric spark alloying in the nanostructuring of the surface layer of carbon steels. (Materials and methods) The authors conducted study of the surface layer of 35-carbon steel with coatings obtained by electric spark alloying on the BIG-1 installation with different materials (Cu, Zn, W and WC) and at different modes. To study the surface layer, the elemental content was studied by x-ray fluorescence spectroscopy, the surface profile was studied by profiling, metallographic studies and microhardness measurements. (Results and discussion) The authors revealed that the chemical composition of the alloying electrode and treatment modes have a direct impact on the saturation of the surface layer with alloying elements, the parameters of the profile of the treated surface, the continuity and mechanical properties of the coating. It was found that harder processing modes increase productivity, but reduce mechanical properties. It was also found that the modified structure of the base material contains nanostructured elements because of electroscopic alloying. A sharp increase in the mechanical properties of the coating material allows suggesting that elements of the nanostructural range are present in the coating. (Conclusion) The conducted research shows that the method of electroscopic alloying can be used for nanostructuring of the surface layer of carbon steels.

Vibroplasma hardening of the working bodies of agricultural machines

The article describes the technology of hardening the working bodies of agricultural machines based on the use of the electric spark energy and vibration arc discharges or the energy of vibroplasma. (Research purpose). The research purpose is studying of the influence of vibroplasma treatment on the physical and mechanical properties of 65G steel, which is the main material of many working bodies of agricultural machinery. (Materials and methods). The studies were carried out on samples from a coulter disk of 30x30 mm with a thickness of 2 mm. The processing was carried out at VDGU-2 technological installations of electric spark alloying in accordance with the patent of the Russian Federation No. 2655420 and vibration arc hardening. Tungsten-cobalt and copper-graphite rods with diameters of 4 and 8 mm were used as electrodes. (Results and discussion). In contrast to the initial sample, the spectrum of the relatively large area of the 65G steel sample hardened by electrospark treatment showed that cobalt (4.92 percents) and tungsten (16.83 percents) are present in the treated layer in appreciable amounts. Measurements of the elemental composition of the local processing zone showed that the main components of this region are tungsten (64.20 percents) and cobalt (7.55 percent). Carbon, nitrogen, oxygen, iron, manganese, calcium, silicon, aluminum, and a number of other elements are present in the surface layer of the sample with a vibratory arc treatment, but at lower concentrations in comparison with the listed elements for the sample with electric spark treatment. It has been found that the main phases are carbide and iron oxide, as well as metallic iron. After treatment with vibroplasma, there is a so-called zone of thermal influence near the treated zone. (Conclusions). The surface layer formed by processing parts by vibroplasma represents a new composite structure consisting of three layers. The hardening of the base material in the depth of the part during electrospark machining occurs at 0.5-1.0 millimeter, with vibroplasma machining it is up to 3-4 millimeter. The microhardness of the surface layer of products increased by more than three times.

Use of Modern Resource-Saving Methods in Parts' Manufacturing and Repairing on the Example of Electric Spark Alloying (ESA)

The work is devoted to a universal resource-saving method of parts processing - electric spark alloying (ESA). It is used both in manufacturing and repairing. This method allows you to apply reinforced and restored coatings to various objects (parts, tools, and tooling) regardless of their shapes and sizes.Purpose of reseach is to show high universality and efficiency of ESA method on the examples of its practical application for problem solving of machine-building production and repair.Methods. The work is analytical and carried out taking into account authors' practical experience.Results. Some information about ESA method, coating forming mechanism, their thickness and properties is given. Implementing strengthening technologies wear resistance is increased by 2-5 times and more by coatings of increased hardness using electrodes from metal-ceramic hard alloys based on carbides of TiC, WC and other hard compounds. The expediency of recovery technologies is shown: wear of most parts (about 85%) of various techniques does not exceed 200 um and their recovery cost is usually no more than 25-30% of a new part cost; recovered parts resource is commensurate or exceeds new parts resource. Adjusting and restoring technologies are described using specific examples.Conclusion. Given examples of practical application of ESA method confirm high universality and efficiency of this method for solving machine-building and repair production problems. Obtained results can be used in method selecting for strengthening or reducing of various objects from metals and alloys (parts of machines, tools, technological equipment) taking into account ESA advantages.

Study of Electric Spark Coatings Properties Obtained by Electrodes from Titanium Electroerosive Particles

Purpose of reseach. Modern car is a very complex system which has about 15... 20 thousand parts. More than 7 thousand lose their initial characteristics during operational process. As practice shows, more than 4000 car parts lose their operability much earlier than the expiration of vehicle life as a whole. These factors lead to significant repair costs, as well as profit losses caused by long delays in part of the rolling stock. Efficiency and qualitative improvement growth of various areas of public production pose new and more complex tasks to increase the efficiency and reliability of parts. These tasks can be solved both by creating special innovative materials and by developing and introducing into production the latest methods of car parts strengthening and applying protective coatings. Electric spark alloying of metal surfaces is one of these methods. Electric spark alloying is widespread in most industries, including automotive manufacturing, mechanical engineering and metalworking. Electric spark alloying method provides high degree of adhesion, high efficiency and low energy consumption. Electrodes with nano particles are of greatest interest. The most promising method is electroerosive dispersion used in the production of nano materials. The purpose of the work is to study coatings' properties obtained by electric spark alloying using powder electrodes made from electroerosive particles obtained in distilled water from titanium alloy wastes of grade ВТ6.Methods. ВТ6 grade chips were used to prepare titanium powder by electroerosive dispersion. Consolidation of the particles received by electroerosive dispersion of BT6 titanic alloy waste is done by spark plasma agglomeration method with the use of spark plasma agglomeration system of SPS 25-10. UR-121 installation was used to cover electrospark coverings. Experimental pictures on QUANTA 600 FEG raster (scanning) electronic microscope were made to study coverings' form and morphology. X-ray spectrum analysis was performed by EDAX 's energy dispersion X-ray analyzer built into QUANTA 600 FEG raster electron microscope. Surface roughness of samples was examined on SURTRONIC 25 profilometer.Results. It was experimentally stated that titanium, oxygen, aluminium and tungsten are the main elements in the sintered sample of titanium particles obtained in distilled water. It was stated as a result of properties investigation of powder electrodes from electroerosive particles and coatings obtained by electrospark alloying. Other elements are present in minor amounts. Roughness of electric spark coated samples is Rz 13.2 um (Ra 2.14 um). These particles obtained in water distilled from ВТ6 titanium alloy waste can be used for electrodes suitable for automotive parts recovering by electric spark alloying.Conclusion. Obtained results can be used in creation of resource-saving processes of metal alloys and composite materials.

Microstructure of a High-Strength Aluminum Alloy after Combined Surface Hardening

Carbide–boride coatings applied on both sides of V96Ts aluminum alloy samples by electric spark alloying (ESA) are metallographically studied. The coated samples are processed by laser on one side. Laser treatment of the surface decreases the pronounced roughness, pores, and cracks visible after ESA. Laboratory tests suggest combined (electric-spark–laser) hardening of the surface of V96Ts aluminum alloy samples to extend the service life of tools and machine parts.

Effect of the Physicochemical Properties of Refractory Compounds and Hard Alloys on Their Erosion in Electric Spark Alloying

This paper presents the results of a multiyear study of the dependence of the erosion of the anode in electric spark alloying (ESA) on the physicochemical properties of its material. This work has been performed using various devices, with different electric modes, using manual or mechanized treatment, and in various media. This article contains generalized data on the anode erosion of refractory compounds and hard alloys. It is shown that the refractory compounds’ erosion occurs at a substantial solid phase participation, whereas the correlation of the erosion value with thermo-physical properties for them is absent. Erosion resistance and the coefficient of the transfer of hard alloys at the ESA initial stage of treatment are both significantly larger than those of a relevant refractory compound, and they increase with the addition of bundle content to the alloy. The law of the additive property of erosion and its dependence on the content of the plastic bundle is not applicable to hard alloys. Porosity enhancements increase the erosion of the anode material.

Hybrid technology combining electrospark alloying, cathodic arc evaporation and magnetron sputtering for hard wear-resistant coating deposition

The novel technology of multilayer coating deposition combining electric-spark alloying (ESA), pulsed arc evaporation (PAE), and magnetron sputtering (MS) in one vacuum process is presented. Layers can be deposited using a single electrode material at operating pressures from 0,1 Pa to atmospheric pressure. The lower ESA layer provides increased substrate toughness, perfect adhesion and a relatively high (up to 100 μm) coating thickness. The upper PAE or MS layer up to 10 μm in thickness provides high mechanical and tribological characteristics. The technology of double-layer PAE–ESA and MS–ESA coating deposition was tested on substrates made of structural and tool steels, titanium alloys using electrodes of cemented carbides (WC–Co, TiCNiAl) and carbon (low-porous graphite).

Effect of the Nature of Electrode Materials on Erosion and Properties of Doped Layers. The Criteria for Evaluating the Effectiveness of Electrospark Alloying

Introduction. The method of electrospark alloying of metal surfaces was proposed by the Russian scientists B. R. Lazarenko and N. I. Lazarenko. It is possible to apply this process to the surface of the workpiece from any conductive materials of a hardened alloyed layer of material to ensure high hardness, heat resistance, wear resistance and other properties of the executive surfaces of the parts. The paper shows the possibility of formulating criteria for determining the efficiency of the electrospark alloying process and the properties of the doped layer, depending on the properties of d-elements determined by their position in the periodic table and a number of (s+d)-electrons of electrode materials. A similar approach to determining performance criteria can be recommended for other high-energy materials exposure processes. Materials and Мethods. The authors used steel 45 as the material of the rim sections and refractory d-metals of IV-VI groups: Ti, V, Cr, Zr, Nb, Vo, Hf, Ta, W; а также d-metals: Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Cd, Re, Os, Ir, Pt, Au and p-metals: Al, Bi, Sb, Sn, Pb as anode materials for creating doped layers. The installations used for electric-spark alloying: EFI-10M, EFI-46A, EFI-25M, EFI-66, Electrom-10, ELFA-541, Elitron-22, IMEI-01-2A; Corona- 1101; microscope MII-4, MIM-10, BIOLAM-M, EMA-100, Axiosplan-2; Profiler P-201 “Caliber”; microthermometry PMT-3M, DUH-W201, Shimadzu. In the study of erosion there we used the installation of “Atovic absorption spectrophotometer, Varian AA-4”. The generator GOS-3OM and installation SLS-10-1 wer used for laser processing. Results. The generalization of the schemes of the process of electric-spark alloying in single and repeated exposure of the model anode material was made. At the cathode there is a hole with a different degree of filling of the cathode material or representing the zone of mutual crystallization of the anode material and the cathode. When exposed to spark discharge in a gaseous medium, there are differences in the formation of holes due to the more intense transfer of eroded material to the opposite electrode, especially to the cathode. Dependences of some properties (microhardness, melting point, elastic modulus) of refractory d-metals on their location in the IV–VI periods of the periodic table are obtained and presented. Dimensional and volumetric relations of d-elements in electrospark alloying were established, depending on their location in the periodic table. Dependences of the properties of model electrode materials on the statistical weight of atomic stable configurations, as well as the dependence of the erosion of the anode of transition metals on the number (s+d)- electrons and the interelectrode medium. The patterns of d-metals erosion under electrospark alloying and other types of high-energy impact to the surface have been found. Conclusions. Based on the results of this research, it can be stated that in order to achieve higher coating properties and greater efficiency of electrospark alloying, it is necessary to give preference to anodic materials having the maximum statistical weight of atomic stable configurations. It can be said that the properties of the electrode materials relate to their erosion amount and the parameters of the efficiency for forming the doped layer during electrospark alloying, which for specific conditions are determined by the method of selection of ratios and comparison with quantitative experimental data of previously established dependencies. A common approach to the formulation of criteria for imparting new properties to materials by high-energy impacting on them is possible. There is formulated a hypothesis for determining similar change dependences of the physical and operational properties of d-elements on their location in the periodic Table and the statistical weight of atomic stable configuration for various methods of local high-energy impact.

Surface Hardening of 40KH Steel by Electric-Spark Alloying

We substantiate the possibility of application of the method of electric-spark alloying of the surface layers of 40Kh steel by electrodes made of Т15К6 and VK8 hard alloys for the purposes of hardening of the working surfaces of elements of the drilling equipment. It is shown that, as a result of local electric discharges between the cathode and the anode, the surface layers can be alloyed with Co, W, and Ti down to a depth of 10–20 μm. It is established that, in order to guarantee the serviceability of surfacehardened elements under severe operating conditions, it is necessary to get a sufficiently high microhardness of the surface layer, optimize the sizes and density of oxides in this layer, and to minimize the residual tensile stresses responsible for cracking. To get the best combinations of these characteristics, we optimize the technological parameters of electric-spark alloying.

Erratum to: Electric-Spark alloying technology for improving the working life of steam turbine rotor blades and equipment for its implementation

Erratum to: Electric-Spark alloying technology for improving the working life of steam turbine rotor blades and equipment for its implementation

MICROANALYSIS OF ELECTROSPARK COATINGS BASED ON ELECTROEROSION POWDERS

The development of modern engineering requires improvement of quality, reliability and durability of parts, assemblies and mechanisms. One of the efficient ways to solve these problems is to applyf functional coatings obtained by the method of electric-spark alloying (ESA). Main electrode materials are mostly sintered hard alloys, which cost due to expensive tungsten in them is relatively high. To solve this problem, a VK8 (90%) hard alloy powder (as a main part) and 10% of high speed steel powder, Gr. R6M5 are proposed to be used as an electrode material. One of the promising methods to produce powders from almost any conductive material, including hard alloy and high speed steel wastes, is the method of electroerosion dispersion (EED), characterized by relatively low energy costs and an environmentally friendly process. The aim of this work is to perform a microanalysis of a steel 30KHGSA section substrate and electrospark coating obtained by electrospark alloying by UR-121 using electrodes of a mixture of electroerosion powders VK8 (90%)+R6M5 (10%), obtained by electroerosion dispersion of hard alloy and high speed steel wastes in illuminating kerosene. To obtain a micro and nano powder of hard alloy and high speed steel wastes a unit for electric erosion dispersing of conductive materials was used. Microanalysis was performed by means of an inverted optical microscope OLYMPUS GX51. The microanalysis allowed us to determine the shape and size of individual grains and their relative positions to identify the presence of inclusions and microdefects and to judge on the properties of the substrate (30KHGSA) and the coating (VK8+R6M5).

Structure, Properties, and Use of Protective Cermet Coatings Prepared By Electric-Spark Alloying and Electric-Arc Hardfacing

Research results are given for study and use of cermet electrode materials, intermetallics, materials based on MAX-phase and ceramic materials with a nanosize structure for application of protective coatings by electric-spark alloying and electric-arc hardfacing on a metal substrate. The microstructure and properties of the alloy and hardfacing layers formed, and the nature of substrate material interaction with SHS-electrodes are studied, and comparative tribological tests are performed for coating strength. Some results of industrial testing of the materials developed are provided.

Tribological properties of combined molybdenum coatings formed by electric-spark alloying on stainless steel

To improve the operational properties of the parts of machines made of quenched stainless steel 30X13, the surface were hardened by electric-spark alloying (ESA) with combined coatings (molybdenum + chromium and molybdenum + bronze). The results of investigations showed the correlation between the wear resistance of coatings and their hardness. It has been noted that the roughness of all alloyed coatings after tribological tests lowered, while the roughness of unalloyed surface of steel 30X13 increased. The smallest coefficient of friction has been established for samples alloyed with the molybdenum + bronze combined coating.

Electric-Spark Alloying Technology for Improving the Working Life of Steam Turbine Rotor Blades and Equipment for its Implementation1

Work is devoted to studying development of technology for forming erosion-resistant coatings for steam turbine rotor blades by electric-spark alloying. Comparative analysis is provided for current methods of steam turbine rotor blade strengthening and repair. It is shown that electric-spark coating formation on leading edges is important, and development of forming technology is connected with a search for new materials. New engineering solutions are found for coating formation from cobalt stellites, the properties of cobalt stellite and cermet hard alloy VK8 electric-spark coatings are studied, and the effect of operating unit parameters on coating formation is demonstrated. New vibrator structures are created for forming electric-spark coatings making it possible to expand the range of electrode vibration to 260 Hz, and specimens are prepared for testing with coating formation.

CREATION OF FUNCTIONAL COATINGS ON MILD STEEL SURFACE AT MULTI-STAGE ELECTRIC-SPARK ALLOYING BY CHROME AND GRAPHITE IN SATURATED ENVIRONMENTS

Established that the multi-stage Electric-spark alloying (ESA) by chrome and graphite, whichoccurs in different environments (air, argon, propane-butane), improves of steel mark 3 surfacemicrohardness to 15 GPa and durability 8 - 32.5 times. This is due to the presence of carbides,nitrides in the surface layers, which were formed by the interaction of anodes materials withelements of saturated environmens (nitrogen, carbon) for extreme process conditions ESA.