Electric-spark Alloying Research Articles

Cermet coatings obtained by electric spark alloying to increase service life of dental instruments

The article presents the results of our study of protective cermet coatings obtained by the method of electric spark alloying on a dental instrument (excavator) using SHS (self-propagating high-temperature synthesis) electrodes based on TiC-NiCr. The influence of discharge energy during electric spark alloying on the roughness, thickness, and proportion of the TiC carbide phase in the cermet coating has been established. It has been shown that during electric spark alloying, the material of the used SHS electrode and the surface of the substrate melt, their convective mixing occurs, and during crystallization, coatings are formed that consist of a strengthening phase TiC and iron-based solid solutions: Fe9.64Ti0.36, F1.88C0.12, and Cr-Ni-Fe-C. It has been found that the maximum size of TiC grains is formed on the surface of the cermet coating, and as they approach the substrate, their size decreases to less than 10 nm. It has been found that the microhardness of the surface of the resulting cermet coatings increased to 6.2 times compared to the microhardness of the original metal base, which was 2 GPa. The results of scanning electron microscopy and energy dispersive analysis of the surface of samples with and without cermet coating before and after corrosion tests are presented. The influence of disinfectants (2 and 100 % Trilox, Wendelin, MegaDes-ortho) on the corrosion resistance of samples with and without developed protective cermet coatings at room and elevated temperatures up to 50 °C and their exposure for 120 h has been established.

Composition, Structure, and Wear Resistance of Surface Nanostructures Obtained by Electric Spark Alloying of 65G Steel

Composition, Structure, and Wear Resistance of Surface Nanostructures Obtained by Electric Spark Alloying of 65G Steel

ПРИМЕНЕНИЕ ВТОРИЧНЫХ ПОРОШКОВЫХ МАТЕРИАЛОВ ДЛЯ ВОССТАНОВЛЕНИЯ БРОНЗОВЫХ ДЕТАЛЕЙ ГИДРОМАШИН

During the operation of agricultural machinery, machine parts and their connections lose their operability, which requires their replacement. The cost of restoration is 50-60 percent of the cost of a new part. The presence of non-ferrous metal and alloy parts in the equipment, and in particular bronze, makes the issue of restoration even more urgent due to the high cost of such parts. Methods using powder materials are particularly successful in restoring worn parts. It is characteristic that in order to reduce the cost of such technologies, it is possible to resort to recycling of metal waste and obtain powder by electroerosive dispersion without special economic costs. (Research purpose) The research purpose is studying the restoration of bronze parts of hydraulic machines with secondary powder materials and analyzing the tribotechnical indicators of the coatings obtained. (Materials and methods) The following equipment was used in the work: an Elitron-52B pulse generator, a scanning electron microscope, a spark plasma sintering unit, an electric spark alloying unit, an X-ray fluorescence spectrometer, a metallographic microscope, a tribometer, analytical scales, a drying cabinet, a set of sieves. (Results and discussion) Electrodes were made from bronze powder obtained by the method of electroerosive dispersion. Using electric spark alloying, samples with coatings from a standard and a new obtained electrode were created. The tribotechnical properties of these coatings were compared. Metallographic and chemical analyses were performed. (Conclusions) The coatings obtained with the new electrode showed the best tribotechnical characteristics in dry friction. At boundary friction, their performance was worse, which may be due to an incorrect choice of lubrication, modes of electric spark alloying and a violation of the technology for obtaining the electrode itself. In general, the use of secondary powder materials for the restoration of bronze parts is relevant.

Electric spark alloying of steel, titanium and niobium alloys using rotating electrode method

The article presents the results of a study of electrospark coatings on metals and alloys using the rotating electrode method. The influence of various parameters on the formation of an electrospark coating on steel 20, titanium VT1-0, niobium and niobium alloy 5VMTs, on titanium VT1-0, niobium and niobium alloy 5VMTs with subsequent siliconization has been studied. The dependences of the growth of the thickness of the electrospark coating with increasing doping time, current in the circuit, and electrode rotation speed were obtained. It has been established that with increasing thickness of the electrospark coating, the thickness of the silicide layer increases. Electric spark alloying leads to an increase in the heat resistance of steel 20 with an aluminum coating by 1.5—3.0 times, of titanium by 2—9 times, and of titanium with a nichrome coating by 2 times. The heat resistance of titanium with a copper electrospark coating after siliconization increases up to 2—10 times, depending on the thickness of the electrospark layer and the siliconization temperature.

Composition, Structure, and Wear Resistance of Surface Nanostructures Obtained by Electric Spark Alloying of 65G Steel

By a combination of the X-ray phase and fluorescence analyses, it was shown that a hardened layer formed during electric spark alloying of 65G steel using a processing electrode made of T15K6 hard alloy is a nanocrystalline material. The ratio of the crystalline and the amorphous phases in it was achieved by changing the discharge energy. Since an increase in the discharge energy leads to an increase in the surface roughness and its amorphization, there is an optimal value of the discharge energy at which the maximum wear resistance of the resulting nanocomposites is achieved. At E = 0.2 J, the wear resistance of the hardened layer is 7–10 times higher than that of an untreated surface.

Monitoring of numerical simulation of the process of surface hardening treatment of titanium alloys

The paper presents the results of monitoring numerical simulation of the process of surface hardening of titanium alloys VT20 and OT4 by electric spark alloying, which can be used in the design of technological processes for the manufacture of titanium blades of steam turbines. Visualization of the resulting model, carried out using the MatLab computer program, gives a visual representation of the process under study. A good agreement of experimental and calculated (simulated) data allows you to set the parameters of the technological processes of hardening of turbine blades according to the simulation data.

Aluminizing of Metal Surfaces by Electric-Spark Alloying

Aluminizing of Metal Surfaces by Electric-Spark Alloying

BUILDING OF ALLOYED SURFACE LAYER DURING ELECTRIC SPARK TREATMENT OF STEEL 35 BY THE RHENIUM

The results of the study of the effect of the composition and structure of the alloyed layer on the surface of steel 35 during electric spark alloying using rhenium anode material were shown. (Research purpose) The research purpose is investigating the effect of the electric spark alloying of steel with rhenium on the composition and structure of the alloyed layer. (Materials and methods). Rhenium Re (99.99 percent) was used as the anode material, steel 35 was used as the cathode. As equipment - BIG-1, Elitron-22-AM with AG-2 unit, IMEIL installation; SEM EVO-50 XVP "S.ZEISS", RigakuMiniFlex-II diffractometer (Japan), Cu-Ka radiation, ICDD database; VLO-200, VLR-220 scales; PMT-3M microhardometer. The samples were cleaned in an ultrasonic bath. (Results and discussion) The composition and structure of the alloyed layer were investigated. The change in the elemental content of the alloyed layer in depth showed a high Re content near the outer surface of the alloyed layer and at a depth of up to 10-15 micrometers, which rapidly decreased with an increase in depth to 27-30 micrometers in the opposite phase to Fe. It was determined that the formation of the obtained phases in the melt microvanna was accompanied by high temperatures during electric mass transfer. (Conclusions) The results of the study of the effect of the modes of electric spark alloying of 35 rhenium steel on the phase composition and efficiency were shown. They proposed an energy indicator, gave its assessment in comparison with others. It is of interest to continue the study of electrospray doping with rhenium, to clarify the modes that increase efficiency.

METHODS OF RESTORATION OF COULTERS FOR APPLYING FERTILIZERS TO SOIL

One of the most important working bodies of a grain planter, ensuring the quality of sowing, is a coulter for applying fertilizers to the soil. The wear of anchor coulters is a common problem for all modern tillage and sowing machines. Currently, it is advisable to restore worn-out coulters and subject them to hardening in order to reduce the cost of purchasing spare parts, including foreign ones. The most rational method of restoring coulters is HDPE boration. (Research purpose) The research purpose is analyzing the wear of coulters for applying fertilizers to the soil, as well as methods of their restoration. (Materials and methods) Anchor coulters made of 20GL steel were investigated. It was noted that the forms of wear in different parts of the working body have wedge-shaped and sickle-shaped forms; wear occurs on the front surface and on the lateral thickenings, which are necessary for sealing seeds. Various methods of restoring coulters were analyzed, such as electric spark alloying, chemical-thermal treatment, electromechanical treatment, HDPE boration, sputtering, surfacing, diffusion saturation, electrocontact welding. (Results and discussion) It was determined that the most promising method of restoring coulters is HDPE boration due to high productivity, low costs and high wear resistance of the coating. The relative wear resistance of the sample after HDPE boration is six times greater than the reference sample. Due to this, coulters with such a coating are less exposed to abrasive wear and retain their performance longer. (Conclusions) We analyzed the types of coulters, as well as their advantages and disadvantages. It was revealed that the coulters are most often subjected to abrasive wear. It was established that HDPE boration is the most rational method of restoring anchor coulters.

Study of combined method of electric spark alloying and ultrasonic burnishing

Article describe opportunity to increase effectiveness electro spark alloying (ESA) by means to create combined methods (ESA and ultra supersonic smoothing USS). Dates of metallographic researches, roughness surface measurements, wear resistance tests, tests of cyclic alternating characters, full — scale tests. Finally paper introduce optimal interval of technological parameters of ESA and USS.

Modification of anode material VK8 by silicon for electric spark alloying of steel 35

Metal-ceramic coatings on steel 35 were obtained by the method of electric spark processing with different duration of control pulses, using a new electrode material WC—7.5 % Co—7.5 % Si for applying electric spark coatings on steel 35. It is shown that WC particles were deposited into the coating as a result of solid-phase transfer, which intensified with increasing discharge duration. The addition of silicon to WC—Co electrode materials can significantly reduce the coefficient of friction of the formed coatings. In general, the use of WC—Co—Si coatings can increase the heat resistance of steel up to 5 times, reduce the coefficient of friction of steel 35 to 47 %, and increase the wear resistance of its surface from 3 to 10 times.

Research of the regularities of the processes of formation of the surface layer in electric spark alloying

Purpose. Determination of rational parameters of the process of electrospark alloying of 40X steel parts with different types of electrodes. Measurement of the applied layer thickness using the Mora Primus 564 coordinate measuring machine at the customer's plant. To give recommendations on the use of electrospark alloying processing modes in the production process when restoring parts. Research methods are based on effective methods of treatment of metal surfaces and technology of obtaining modified layers by electrospark treatment. Measurements were based on theoretical metrology in modeling instrumental errors of measuring instruments, theoretical principles of instrumentation and mechanical engineering technology. The Mora Primus 564 coordinate measuring machine was used during the measurements. Research results. Electrospark alloying is one of the most common technologies for working with metal, which is characterized by high accuracy and productivity. In addition, high adhesion strength of the applied layer with the base material is provided, and the process itself is easy to perform technological operations and has low energy consumption. The analysis of the main factors influencing the quality of the surface layer during processing is carried out. The process of electrospark alloying of a 40X steel sample was investigated experimentally. During the experiments, modern control and measuring equipment and measurement methods were used. Scientific novelty. For the first time, rational modes of electrospark alloying with vanadium, titanium and tungsten of 40X steel parts have been determined. The dependence of the thickness of the applied layer on the modes of treatment with different electrode material is established. Recommendations for alloying modes in the production process for 40X steel are given. Practical meaning. The experimental researches on electrospark alloying of the 40X steel sample carried out in the production conditions allowed to reveal the basic regularities of the formation of the surface layer and to formulate recommendations for obtaining a coating of a certain thickness. This will restore the worn surface of the part or strengthen the new one.

Operational Properties of Steel Friction Units with Copper-Alloy Antifriction Coating Formed via Electric Spark Alloying

Operational Properties of Steel Friction Units with Copper-Alloy Antifriction Coating Formed via Electric Spark Alloying

Electric-Spark Alloying of Metal Surfaces with Graphite

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.

Study of the structure and properties of protective coatings obtained by the method of electric spark alloying with SHS electrodes (review)

Electric spark alloying (ESA) is a traditional method of obtaining protective coatings on the working surfaces of parts and mechanisms. A review of the results of studying the structure and properties of protective coatings obtained by the ESA method using SHS-electrodes is presented. Ceramic and cermet electrodes are obtained by the method of SHS-extrusion carried out under conditions of combustion processes with high-temperature shear deformation. SHS extrusion makes it possible to obtain electrodes with desired structure and properties in tens of seconds in one technological stage. The results on the study and application of electrode materials made of hard alloy materials, intermetallic compounds, materials based on the MAX-phase and ceramic materials with a nanoscale structure are presented. Analysis of the microstructure and properties of the formed alloy layers showed that the protective coating consists of at least two zones. The sizes of the structural wear-resistant components on the coating surface, usually correspond to their sizes in the original electrodes. When going in depth to the substrate, the grain size decreases and amounts to 20 – 100 nm. It is shown that a protective coating is formed on the surface which increases the mechanical and tribological properties. The presented results can be used in comparative tribological tests of hardened coatings, industrial tests of machined parts, etc.

Research of the interelectrode medium influence on processing results of the steel surface by method of the electric spark alloying

Research of the interelectrode medium influence on processing results of the steel surface by method of the electric spark alloying

Development and research of an automated control system for a lathe DIP-500

Ways for upgrading the DIP-500 lathe for improving the quality and speed up the process of workpiece electric-spark alloying of parts are proposed. Keywords electric-spark alloying (ESA), roll, wear-resistant coatings, lathe, automated control system

THE USE OF POWDER MATERIALS IN THE TECHNOLOGIES OF RESTORATION AND HARDENING OF AGRICULTURAL MACHINERY PARTS

Currently, a large number of different methods for producing metal powders are known. Most of them use ready-made raw materials and semi- finished products made from the source ore, which leads to an increase in the cost of the resulting product, so the issues of recycling of machine-produced waste become relevant. One of the most promising and energy-efficient methods of obtaining powders from any conductive materials is electroerosive dispersion. This method makes it possible to process metal waste and obtain raw materials for technologies for the restoration and hardening of agricultural machinery parts, gives a tangible economic effect. (Research purpose) The research purpose is to consider various methods of obtaining metal powders and to determine the most promising and technologically advanced of them for the restoration and hardening of parts; to justify the feasibility of processing machine-produced waste into powder material as an important resource-saving factor. (Materials and methods) The study uses literature sources, fundamental laws of physics and chemistry, basic laws of metallurgy, used a laboratory installation for electroerosive dispersion. (Results and discussion). The article describes the main methods of obtaining metal powders: mechanical, chemical, as well as a promising method of electroerosive dispersion. The method of electroerosive dispersion is considered the most promising method for obtaining metal powders. This method makes it possible to obtain powders from metal waste from machine- producing industries, suitable for reuse in technologies for the restoration and hardening of machine parts of agricultural machinery by iron, various types of surfacing and electric spark alloying. (Conclusions) Powder metallurgy provides valuable raw materials for the technologies of restoration and hardening of parts. In order to save money, it is advisable to obtaining metal powders from machine- produced waste. The method of electroerosive dispersion is characterized by relatively low energy costs and environmental cleanliness of the process.

Effect of Chromium Addition and Regimes during Electrospark Alloying with Aluminum Matrix Anode Material of Steel 45

Introduction. Electrospark alloying is used to produce hardening coatings. Anodic materials with unique properties include metal matrix composites based on aluminum. The aim of the work is to develop new aluminum matrix anode composite materials with high efficiency indicators during electrospark alloying of carbon steel 45. Materials and Methods. Structural carbon steel 45 was used as the substrate (cathode). Aluminum matrix materials are chosen as the anode materials. The value of the cathode weight increment and the anode erosion were determined by the gravimetric method on the Shinko Denshi HTR-220 CE electronic scale with an accuracy of ±∙10–4 g. To study the microstructure and metallography of the surface of the anode materials, the microscopes EVO-50 XVP and Altami MET 3 APO from S. ZEISS were used. The device CALOTEST CSM Instruments was used to study coatings for microabrasive wear. Results. There is developed a methodological scheme for achieving the efficiency of the electric spark alloying parameters and the properties of the doped layer depending on the composition of the anodic metal matrix composite material based on aluminum with the addition of chromium and processing modes. The mode of Institute of Materials Science electrospark installation with pulse energy of 14.4 J was set for anode material application during electrospark alloying. It is established that after electric spark alloying of steel 45, the hardness and wear resistance of the surface increase by 2-3 times, and the heat resistance ‒ by 5–18 times. Discussion and Conclusion. The series of increasing the cathode mass, the erosion resistance of the electrode materials, mass transfer coefficient, heat resistance, hardness and wear resistance of the alloyed layer are obtained. The obtained series are a convenient tool for achieving various efficiency parameters in electric spark alloying depending on the selected anode material and processing modes.

МАТЕМАТИЧЕСКАЯ МОДЕЛЬ ЭЛЕКТРОИСКРОВОГО ФОРМИРОВАНИЯ ИЗНОСОСТОЙКИХ ПОКРЫТИЙ НА ОБРАБАТЫВАЕМЫХ ПОВЕРХНОСТЯХ

The article considers a new direction in optimizing the process of plasma hardening of the surfaces of cutting elements of agricultural machines based on the use of electric spark discharge energy. (Research purpose) The research purpose is in optimizing the technological process of hardening the surfaces of cutting elements of agricultural machines by the method of electric spark alloying of carbide material elements. (Materials and methods) A device under RF patent No. 2655420, developed by the scientific supervisor of the subject S. N. Sharifullin, was used for electric spark alloying. A tungsten-cobalt rod with a diameter of 4 millimeters, consisting of 94 percent tungsten and 6 percent cobalt, was used as the electrode material for this case. The processed sample of 65G steel, which is the main material of the working bodies of tillage equipment. The physical and chemical properties of the samples were studied with a scanning electron microscope EVO 50 XVP from Zeiss. (Results and discussion) After the electric spark treatment of the alloyed elements, there were about ten, while their spectra also appear at different irradiation energies. The alloyed elements in the surface layer are not only separate, but also in the form of compounds with other elements. Such alloying elements as carbon, cobalt and tungsten appeared in a noticeable amount in the surface layer. Electric spark treatment allows increasing the microhardness of the surfaces of cutting elements of tillage equipment up to three times. (Conclusions) When developing a mathematical model of the electric spark formation of wear-resistant coatings on the treated surfaces, it is necessary to use the energy conservation equations of the electron gas, the Maxwell equations, the continuity and momentum equations. The complex solution of these equations makes it possible to obtain the required output parameters depending on the input ones.