Electrospark Treatment Research Articles

Выбор режимов электроискровой обработки для электродов из спеченной бронзы

The method of electrospark machining has proven itself well in the technology of repair and restoration of parts. The operational properties of coatings obtained by this method depend on the microstructure, chemical and phase composition of the electrode materials. A significant improvement in operational properties, for example, wear resistance, is achieved by the formation of nanostructured coatings using electrodes with a certain content of alloying nanomaterials. It is possible to obtain such materials at the lowest cost by electro-erosion dispersion of machine-building waste. This article discusses the electrodes obtained by sintering bronze powder obtained by the method of electroerosive dispersion. Such materials are new for the process of electrospark machining; therefore, it is important to study and select the optimal application modes, since a qualitative characteristic of the process is the indicator of the transfer of the electrode material to the part, which depends on the processing modes and installation parameters. The aim of the study is to select the modes of the installation for electrospark treatment for optimal deposition of the material, as well as to study the degree of coating increment during electrospark treatment. Coating was carried out using an installation for electrospark treatment mod. «Westron» type AI-007, electrode material was obtained by the technology of spark plasma sintering of bronze powder, surfacing was carried out on steel samples 14 × 14 × 40 mm in size, the work also used an Acculab ALC-210d4 analytical balance and an MG micrometer Н25 GOST 6507-90. All coatings were applied to samples with an equal area in three layers under different processing conditions. After that, the increment in the thickness and mass of the electrode material on the sample surface was measured. Based on the results of the work, formulas were obtained and graphs were built. The most optimal mode of coating with an electrode made of sintered bronze obtained from machine-building waste by the method of electroerosive dispersion was determined, which proves the consistency of this method of obtaining electrode materials.

DEVELOPMENT OF DEVICE FOR RESTORATION OF PLACES FOR BEARINGS

Defects of case details include operation of openings under bearings within 0,2 - 0,4 mm on the party, operation of landing belts under sleeves. When restoring them, traditional methods are used: installation of repair bushings, application of polymer and electrolytic coatings, micron smelting, electrospark treatment, etc. Restored parts must have hardness and wear resistance with the parameters of the material of the reducing part (deviation 10 - 15%), have sufficient adhesion to the base metal, corrosion resistance in a humid environment, provide maximum contact area with the conjugate part, no pores, slag, foreign inclusions . The method of restoration must eliminate the thermal impact on the part and be cost-effective. Polymer compositions are usually brittle, subject to breakage and leaching. Surfacing causes warping of the part, bleaching of cast iron, the formation of slag and pores in the deposited layer. The electrospark coating method does not provide sufficient contact area with the conjugate part. The use of electrolytes for iron seats in some enterprises is aggressive, unstable, requires heating or the use of expensive thyristor power supplies, followed by machining, as the microhardness of precipitation reaches a large value depending on the composition of the electrolyte and process modes, have high internal voltage. The proposed device for restoring the bearings simplifies the existing method and meets the technical requirements of manufacturers in terms of machining accuracy (ovality, taper, coaxiality and surface roughness), provides high productivity (2 times higher than the productivity of specialized machines horizontally). and low cost (60 times lower than the cost of specialized machines).

Friction and Wear of Electrospark Coatings Made of Molybdenum, Bronze, and Combined (Ti + Al + C) Composition on Steel 45 in a Lubricant Medium

This paper discusses the topical issue of the general compatibility of tribological pairs from the point of view of wear resistance when using various electrospark coatings. For investigation, steel segments were coated with bronze, Mo, and combined Ti + Al + C coatings by electrospark treatment. Coated segments and uncoated control segments were studied in a friction pair with an unhardened C45 steel roller (15HRC) at loads of 300 and 600 N in a lubricant medium. Throughout the test, the coefficient of friction was measured, the wear rate of the tested tribo-pairs was estimated, and the nature of the wear of the friction surfaces after testing was analyzed using optical and scanning electron microscopy (SEM). The results have shown that the most compatible tribo-pairs were steel 45/Bronze and steel 45/Mo, since they have exhibited the best resistance, i.e., the least wear under both loads tested.

Improvement of Ti6Al4V-Alloy Wear Resistance by Electric-Spark Hafnium Carbide Coatings

In this paper, we obtain cermet coatings with a thickness of 19 to 22 μm by the method of electrospark treatment of titanium alloy Ti6Al4V in a mixture of titanium granules with hafnium carbide powder. An increase in the volume fraction of hafnium carbide powder in the mixture of granules from 2.4 to 6.7 vol % led to an increase in the concentration of the hafnium carbide phase HfC in the coatings. The coating structure is represented by a metallic Ti–Hf–C binder with large inclusions of hafnium carbide. The average microhardness of Ti–HfC coatings was in the range of 7.1–8.3 GPa, which is 2–2.5 times higher than that of the Ti6Al4V alloy. Wear tests in dry sliding mode showed that Ti–HfC coatings had a wear rate in the range from 3.18 × 10–6 to 1.5 × 10–5 mm3/(N m), which is 25 to 250 times higher than that of Ti6Al4V titanium alloy.

Study of the influence of electro-spark treatment on whey protein

Study of the influence of electro-spark treatment on whey protein

Reactive phase formation during electrospark treatment of the EP741NP alloy with fusible Al – Si electrode

An appoach for hardening and smoothing surface of a nickel based alloy EP741NP using preparing low-melting structurally homogeneous electrodes by quenching the melt and certain regimes of electrspark treatment was tested. Electrodes with eutectic (Al – 12Si) and hypoeutectic (Al – 9Si) compositions were specially prepared by melt quenching, which aimed structural refinement and chemical homogenization. These electrodes were used for electrspark surface treatment of the EP741NP alloy. The wear resistance of the surface was estimated at tribological tests. It is demonstrated that reactive phase formation, i. e. synthesis of phases that are not present in either the electrode or the substrate, is achievable when applying a longer pulsed discharge during electrospark treatment. In this case, intermetallic phases (Ni3Al, AlCo) form and the surface roughness is low: Ra = 1.98 μm, which is due to plasma sparks smoothening humps and filling in cavities by melt. Smoother layers have higher wear resistance, and a higher severe wear of the counter body is indicative of their high hardness. High-frequency electrospark treatment with shorter pulse discharges leads to reactionless mass transfer of the ductile FCC Al-based solid solution resulting in a complete wear of the modified layers during tribotesting.This research was funded by the Russian Foundation for Basic Research (Project no. 19-58-18022), in part of improving the quality of surfaces obtained by additive technologies using reactive electro-spark treatment and by the Ministry of Education and Science of Russia at frame of a governmental assignment (Project no. 0718- 2020-0034) in part of microscopy investigations of structural and phase transformations.

The Morphology and Mechanical Properties of ESD Coatings before and after Laser Beam Machining.

Electro-spark deposition (ESD) and laser beam machining (LBM) are the technologies using the concentrated energy flux. This paper deals with the issue of the impact of laser modification on the morphology and mechanical properties of carbide/copper coatings produced by electro-spark treatment. The coatings were applied to C45 carbon steel samples using the EIL-8A device. The following three types of electrodes made using the powder metallurgy (PM) hot pressing technique, from copper and tungsten carbide powders of different percentage compositions, were used for the coatings: 25% WC and 75% Cu; 50% WC and 50% Cu; and 75% WC and 25% Cu. Laser modification of the surface layers was performed with an Nd:YAG laser. The research focused on the analysis of the morphology of coatings applied by electro-spark technology before and after laser processing. The analysis of the morphology of electro-spark coatings revealed that the coatings had microcracks and pores. The laser beam machining of ESD coatings led to the homogenization of chemical composition, fragmentation of the structure, and elimination of microcracks. In addition, measurements of porosity, microhardness, adhesion, and analysis of XRD phase composition of the electro-spark coatings were performed. Laser processing proved to have a positive effect on improving the adhesion of coatings and reducing their porosity. This paper also presents a simulation model of heat transfer processes for the case of laser radiation impact on a WC-Cu coating. The developed numerical model, describing the influence of laser treatment on the distribution of temperature fields in the heated material (at a given depth) is of significant importance in the development of treatment technologies. Laser-modified ESD coatings perform anti-wear and protective functions, which enable their potential application in means of transport such as rolling stock.

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.

Deposition of Amorphous Hardening Coatings by Electrospark Treatment in a Mixture of Crystalline Granules

This article is devoted to the formation of amorphous coatings on the steel 35 surface by electrospark treatment in a mixture of crystalline granules. It is revealed by the energy dispersive X-ray spectroscopy (EDS) that formed coatings contain W, Mo, Co, and Ni in various ratios. The weight of granules of various compositions decreases by 11–16 wt % for 6-h treatment due to electric erosion. The mass transfer coefficient varies in a range from 33 to 54%. X-ray structural analysis showed the prevalence of an amorphous phase (81–99%) in the structure of deposited layers. Annealing of coatings at a temperature above 1150°C leads to the crystallization of the amorphous phase into boron carbide of the M23(C, B)6 type, as well as into α-Fe. The coatings have an increased hardness of 10–15 GPa, while their wear resistance in the dry sliding wear mode under loads of 10 and 50 N is higher than for steel 35 by a factor of 3.3 and 1.6. The coating friction coefficient is lower than for steel 35 by 13–30% and was 0.27–0.31. The wear resistance of coatings in a dry abrasive wear mode is higher by a factor of 3–5 when compared with uncoated steel 35. The best characteristics are inherent without nickel and worst are inherent without cobalt. Thus, it is established that tungsten and cobalt increase the wear resistance of iron-based amorphous alloys, while nickel and molybdenum tend to worsen their tribotechnical behavior.

Получение аморфных покрытий электроискровой обработкой стали 35 в смеси железных гранул с CrMoWCBSi порошком

Получение аморфных покрытий электроискровой обработкой стали 35 в смеси железных гранул с CrMoWCBSi порошком

Mass Transfer of a Nanocrystalline 5BDSR Alloy during Low-Voltage Electrospark Treatment

A mathematical dependence is obtained to calculate the electrode material mass transferred from an anode to a cathode during low-voltage electrospark treatment. The mass transfer of a nanocrystalline 5BDSR alloy is experimentally studied. The difference between the calculated and experimental data is at most 10%.

Studying the effect of electrospark treatment of milk whey on the process of its fermentation and quality of thermoacid cheese

The paper reports a study into the influence of electrospark dispersion of current-conductive granules of magnesium and manganese in the environment of milk whey on the process of its fermentation in the technology of making soft thermo-acid cheeses the type of Adyheyskyy.The object of this study was milk whey, obtained from the thermo-acid settling of cheeses. To prepare the coagulant, it was treated in an electric discharge chamber with a current-conductive layer of magnesium or/and manganese granules manganese over 30...120 s.It has been established that the result of such a treatment of milk whey is the increased magnesium content, by 1.8 to 4 times on average, and the increased manganese content, by 1.5 to 3.8 times on average, depending on the treatment duration.It has been proven that it was characteristic, of all the examined samples, to demonstrate a natural growth of titrated acidity during fermentation. However, the samples enriched with mineral elements following the electrospark treatment over 30...60 s have shown a more intensive growth in titrated acidity. Similar results were obtained when using milk whey from cottage cheese. Although at the initial stages of fermentation (0...6 hours) the increase in acidity was somewhat slower, which has an objective explanation related to the effect of enhanced acidity of the starting whey (50...60 °T) on lactobacilli.It was established that the production cycle is significantly reduced in case of using the proposed technology of acidic whey-coagulant for making thermo-acid cheeses.There is also an increase in the utilization coefficient of technological equipment and its resources. A given technology does not require significant areas for the introduction of an innovative electro-physical technique, and, instead, given the reduced fermentation time, it contributes to reducing the number of containers involved in the preparation of coagulant.It has been established that the use of acidic whey, produced from raw materials enriched with magnesium and manganese, in the technology of thermo-acid cheese contributes to its enrichment with valuable mineral elements. It also provides for a more complete use of the protein potential of milk and, consequently, increases the thermo-acid cheese yield by 1.8...6.5 %

Deposition of amorphous hardening coatings by electrospark treatment in a crystalline granule mixture

The article focuses on the preparation of amorphous coatings on the Steel 1035 surface by electric spark treat the coating composition control by changing the granule mixture composition was studied. EDS analysis showed that the coatings obtained contain W, Mo, Co and Ni in different ratios. The weight of granules having different compositions decreased by 11–16 wt.% in 6 hours of treatment as a result of electric erosion. The mass transfer coefficient varied from 33 to 54 %. X-ray diffraction analysis showed the predominance of the amorphous phase in the composition of layers deposited. Annealing of the coatings at 1150 °C led to amorphous phase crystallization into M23(C,B)6 type borocarbide and α-Fe. The coatings had an increased microhardness of 10–15 GPa, and their wear resistance under dry sliding wear conditions at 10 and 50 N loads was 3,3 and 1,6 times higher, respectively, than in Steel 1035. The highest values at both loads were shown by samples without nickel, while samples without tungsten featured the lowest values. The coatings had a friction coefficient within 0,27–0,31 that is lower than for Steel 1035 by 13–30 %. Wear resistance of the coatings under dry abrasive wear conditions at the 25 N load was 3 to 5 times higher as compared to uncoated Steel 1035. Samples without nickel demonstrated the best performance, while samples without cobalt had the worst indicators. Thus, it was shown that tungsten and cobalt increase wear resistance of iron-based amorphous alloys, while nickel and molybdenum tend to worsen their tribotechnical behavior.

Стан поверхні та структура наночастинок, отриманих електроіскровою обробкою марганцевих гранул

Стан поверхні та структура наночастинок, отриманих електроіскровою обробкою марганцевих гранул

Электроискровое осаждение покрытий с использованием порошка Cr3C2 и их характеристика

A mixture of titanium granules with chromium carbide powder Cr3C2 was employed to prepare Ti-C-Cr coatings on Ti6Al4V titanium alloy using electrospark treatment in granules. Three mixtures of granules with a chromium carbide content of 2.7; 5.1 and 7.4 vol.% were prepared. According to X-ray analysis, it was found that titanium carbide, αTi, chromium and carbide Cr7C3 were observed in the composition of coatings. Titanium carbide was formed as a result of decarburization of Cr3C2 when interacting with molten titanium under the action of electric discharges. The average thickness of the coatings increased from 18 to 34 μm with an increase in the content of Cr3C2 powder in the mixture of granules. Grains of titanium carbide with a dendritic structure, surrounded by a Ti-Cr binder, were observed in the microstructure of the coatings. According to the EDS data, the concentrations of chromium and carbon decreased when scanning from the surface layers of the coating to the substrate. With an increase in the concentration of Cr3C2 powder in the mixture of granules from 2.7 to 5.1 vol.% hardness of coatings increased from 5.2 to 10.6 GPa. This is 1.7 – 3.5 times higher than that of the Ti6Al4V alloy. Dry sliding wear tests showed that the Ti-C-Cr coatings had a wear rate ranging from 0.41 to 2.38 ×10−6 mm3 / Nm. Thus, these can improve the wear resistance of the Ti6Al4V alloy from 18 to 107 times. Testing of the samples for resistance to high-temperature gas corrosion at 900°C for 100 hours showed that the technology of electric spark treatment in a mixture of titanium granules with 7.4 vol.% of chromium carbide powder allows increasing the oxidation resistance of the alloy Ti6Al4V three times.

Catalytic Activity of FeCrNiWMoCoCB Metallic Glass Coatings on a Metal Support in Dye Wastewater Treatment

Catalytic activity of FeCrNiWMoCoCB metallic glass (MG) coatings deposited on steel 1035 was studied in decomposition of the model solution of methylene blue. Five samples with different compositions and predominantly amorphous structure were synthesized by depositing MG coatings using the electrospark treatment in the crystalline alloy granule medium. The Ra criterion characterizing the coatings roughness was 9 to 14 mm that indicated the considerable area of interaction between MG and methylene blue. The presence of nickel and cobalt but not tungsten and molybdenum in the metallic glass favored an increase in the catalytic activity of the coatings. The best catalytic properties were inherent in the coatings consisted of Fe33Cr8Ni8W8Mo8Co8C16B11which provided a decrease in the activation energy of self-decomposition of methylene blue to one eighth in the presence of hydrogen peroxide. It was shown that the efficiency of this catalytic system could be increased by a factor of 3 upon etching in 30 % HNO3for 380 s due to an increase in the porosity and in the specific surface area of the coating. The suggested approach makes it possible to decrease considerably the prime cost of the catalytic units of the reactor owing to application of one-stage supporting of MG coating on the metals.

On the Application of Carbon-Containing Electrode Materials in Electrospark Alloying Technology. Part 2. Structure and Properties of Two-Layer Coatings

Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a hard-alloy electrode STIM-20H (TiC—20% Ni) and carbon-containing material (graphites and carbon-based composite materials). Phase composition and relief of the coatings formed were analyzed. It was established that with regard to the applied carbon-containing material, the electrospark treatment can decrease the friction coefficient of the coatings and increase wear- and heat resistance of the titanium alloy.

On Application of Carbon-Containing Electrode Materials in Technology of Electrospark Alloying: Part 1. Peculiarities of Coating Formation Using Electrospark Treatment of Titanium Alloy OT4-1

Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a STIM-20N hard-alloy electrode (TiC–20% Ni) and carbon-containing material (graphite and carbon-based composite materials). Kinetics of the mass transfer of the hard-alloy electrode was studied. The cathode mass loss during the first minute of the treatment was established. The kinetics results were processed using the methods of mathematical statistics. The erosion resistance of the applied carbon-containing materials was determined. Phase composition and relief of the coatings formed were analyzed. It was found that the application of the carbon-containing material increases the content of refractory phases in the coatings. Increase in the time of the treatment using the carbon-containing materials decreases the roughness of the coatings.

Вплив режимів електроіскряного оброблення на формування твердих розчинів у стопах міді з залізом і кобальтом

Вплив режимів електроіскряного оброблення на формування твердих розчинів у стопах міді з залізом і кобальтом

Structure and properties of coatings produced by pulsed electrospark deposition on nickel alloy using Mo-Si-B electrodes

The kinetics of the pulsed electrospark deposition of coatings onto a nickel alloy substrate in air using compositions of SHS Mo-Si-B electrodes were investigated. The optimal frequency–energy regime of electrospark treatment (E=0.048J, I=120 A, f=3200Hz, and τ=20μs) characterized by the minimum roughness of the coating surface was determined. The structure, phase composition, and properties of the coatings were comprehensively studied. The wear patterns of the coatings were analysed in tribological tests. The coatings were shown to significantly enhance the hardness, as well as heat and wear resistances, of the nickel alloy and are recommended for use in the protection of critical components.