Electrospark Alloying Research Articles

The use of fractal analysis to assess the influence of electrospark alloying on the durability indicators of hydraulic hammer parts

Abstract. Statement of the problem. In order to increase the wear resistance and fatigue strength of the material of hydraulic hammer parts, it is not always advisable to change the traditional technology of manufacturing the part and, in particular, the methods of its heat treatment. Different types of finishing are applied only specifically to the given product. In some cases, it is worth applying surface strengthening of the product. Purpose and problem statement. The purpose of the work is to evaluate the impact of electrospark alloying on the durability indicators of hydraulic hammer parts. In order to achieve the set goal, it is necessary to: develop modes of electrospark alloying; conduct an analysis of the location of damage zones and their nature on parts strengthened by electrospark alloying, identical to those observed on tested parts manufactured without additional strengthening and with the use of LTO; Apply fractal analysis to evaluate the impact of electrospark alloying on the durability indicators of hydraulic hammer parts. Research material and methods. All details were strengthened by electrospark alloying with tungsten. The power of the processing current was 1 kW. The peak, in addition to strengthening with tungsten, was additionally processed by electrospark alloying with chromium at a current of 1.5 kW. The surfaces processed by electrospark alloying were ground to obtain the roughness of the strengthened surfaces of parts R and 04–08. Experimental results and their discussion. During the micro-examination of areas strengthened by electrospark alloying, which are outside the load zone during the test, it was established that the areas strengthened by electrospark alloying on the body and sleeve have a thickness of 10–40 μm and a hardness of Н V 600–650. On the strikers, the initial thickness of the hardened layer is 20 μm with a hardness of НV 600–650. The strengthened zones in the cross-section have the appearance of arc-shaped, embedded surface layers of metal parts, phases. There are no structural changes under this zone in the main metal. Conclusions. The results of tests of parts strengthened by electrospark alloying show that the wear resistance of the parts is increased by 1.3 times compared to the original state of the parts. Fractal models were obtained, which can be interpreted as a knowledge base for monitoring the strength indicators of the striker body, which allow monitoring its residual resource during operation. It was established that the strength indicators increase when the fractal dimension of the sorbite component increases, since it has better strength indicators compared to the original ferrite-pearlite structure. Indicators of pairwise correlation coefficients of the obtained models are fixed in the interval of values 0.6779...0.9254.

Investigating the effect of electrospark alloying parameters on structure formation of modified nitrogen coatings

Investigating the effect of electrospark alloying parameters on structure formation of modified nitrogen coatings

Investigation of the Structure and Properties of MoS2 Coatings Obtained by Electrospark Alloying

Electrospark coatings alloyed with MoS2 have been studied. The coatings were obtained by the following two strategies: the first consisted of pre-applying molybdenum disulfide to the treated surface and alloying with a molybdenum electrode (Mo + MoS2 coating); the second consisted of applying a paste with a sulfur content of 33.3% to the treated surface and alloying with a molybdenum electrode (Mo + S coating). The structure, phase composition, and tribological properties of the coatings were investigated. The coatings have a complex structure consisting of an upper soft layer, a hardened white layer, a diffusion zone, and a substrate. Element analysis and cross-sectional hardness changes indicated that element diffusion occurred at the coating/substrate interface. The phase composition of the coatings is represented by BCC and FCC solid solutions on Fe, and MoS2 is also detected. In Mo + S coatings, the molybdenum disulfide on the surface is about 8%; in Mo + MoS2 coatings, it is 27%–46%. The obtained coatings show very good tribological properties compared to molybdenum ESA coatings. The frictional forces and coefficients are reduced by a factor of 10 and 40, depending on the test conditions.

Influence of Substrate Surface Quality on Electro-Spark Alloying

Influence of Substrate Surface Quality on Electro-Spark Alloying

Удосконалення параметрів якости поверхневих шарів деталів з криці після алітування методом електроіскрового леґування. Ч. 1. Особливості структурного стану крицевих поверхонь після алітування

Удосконалення параметрів якости поверхневих шарів деталів з криці після алітування методом електроіскрового леґування. Ч. 1. Особливості структурного стану крицевих поверхонь після алітування

Analytical Study of Heat Source Formation on Component Part Surface at Electrospark Alloying

Analytical Study of Heat Source Formation on Component Part Surface at Electrospark Alloying

The Formation of C-S Coatings by Electrospark Alloying with the Use Special Process Media

The paper presents an analysis of technologies for improving the quality parameters of the surface layers of parts, which were carried out by the method of electrospark alloying (ESA) and by additional saturation of surfaces with alloying elements from special process media (STM). The technology of sulfocementation was considered. Metallographic and hardness tests after sulfocementation by ESA showed that the treated surface consists of layers: "soft", hardened and base metal. As the discharge energy increases, the thickness, microhardness and integrity of the coating increase. The presence of sulfur in STM promotes the sulfidation process. It is shown that sulfur accumulates on the surface of the metal at a depth of up to 30 μm. This zone is characterized by reduced microhardness. A strengthened layer is formed under this layer, it has an increased carbon content and high microhardness.

STRENGTHENING OF THE CARBIDE ALLOY OF WOOD CUTTING SAWS WITH COMPOSITE MATERIALS

The article covers issues related to the strengthening of solid tungsten-cobalt alloy plates of wood-cutting disc saws with new tungsten-free composite materials. It is shown that the domestic hard alloy is significantly inferior to the similar hard alloy of foreign production. This is primarily related to the technology of its production (the imperfection of the equipment for grinding tungsten, which does not make it possible to obtain the required dispersion and the method of sintering). It is noted that one of the ways to solve these problems is the development of a technology for strengthening hard alloy plates, which will make it possible to increase the stability indicators of the tool. Wear resistance can be increased by special surface treatment with the help of new composite materials, which changes such properties of the main material as hardness, corrosion and operational wear resistance, and strength. The problem of surface strengthening of wood-cutting tools with the use of wear-resistant coatings is quite urgent, as it opens wide opportunities for the creation of new special materials with fundamentally new physico-mechanical and physico-chemical properties. Advanced technologies for obtaining such coatings include the method of their formation under the action of concentrated energy flows with the use of electrospark alloying. The main advantage of the surface treatment of materials is that despite the high hardness and strength of the surface layer, the high plasticity and viscosity of the base is preserved. That is why research aimed at strengthening wood-cutting saws with new materials using the electrospark alloying method is relevant. The purpose of the research is to increase the service life of the wood-cutting tool by electrospark alloying of hard alloy with new composite materials and to reduce the shortage of hard alloys. The research results showed that dusts with strengthening treatment of teeth with a material based on titanium carbide КТФХ have the greatest resistance.

Electrospark alloying of 30KhGSN2A stee l with alloy based on systems of immiscible components

The studies of the influence of the parameters of the electrospark alloying mode (EIL) on the properties of steel coated on the basis of copper alloys made it possible to determine not only the change in the mechanical and fatigue properties of the material, but also to choose rational technological modes. The rational modes of electrospark coating of bronze VBr5М and BrAZhMCz10-3-1.5, as well as an alloy based on the Cu—Pb system on the surface of parts made of steel 30KhGSN2A at the installation are determined ELFA-512M in automatic processing. It is shown that in order to eliminate the burnout of phosphorus during EIL of parts with bronze grade VBr5M, it is necessary to carry out the process in an inert gas (argon). It has been established that the coating applied by the electrospark method based on bronze does not affect the strength and plastic properties of steel 30KhGSN2A. At the same time, EIL bronze leads to a decrease in the low-cycle fatigue of samples made of steel 30KhGSN2A. Based on the results of studies of the coefficient of friction and wear of samples under dry friction conditions after EIL for the manufacture of parts operating under high loads under sliding friction conditions, taking into account the data of mechanical tests, it is possible to recommend for use bronze grade BrAZhMCz10-3-1.5 and a composite material based on immiscible components of the system 64 % Cu—36 % Pb.

Analysis of the influence of electrospark alloying parameters on the structural state of alloyed surfaces

Рroblem. Among the promising methods of surface hardening and modification are techniques based on the treatment of metals and alloys with high-energy flows of materials and energy. Among the modern methods of metal surface treatment is electrospark alloying (ESA), which allows obtaining surface structures with unique physical, mechanical and tribological characteristics. It is known that alitization provides metal surface layers with protection against corrosion and oxidation at elevated temperatures. The traditional method of forming alitized coatings is chemical-thermal treatment. The paper proposes a method of alitization by ESA. Many parameters influence the formation of the layer during alitization by the ESA method. First of all, it is the energy parameters. Goal. The aim of the work is to evaluate the effect of the ESA alloying process performance on the structure formation. Methodology. The study was carried out on samples of steel 20. An aluminium electrode in the form of a wire was used as a tool electrode for ESA. Different alloying modes were investigated, the discharge energy and performance were changed. The alloying was carried out in two stages. At the first stage, the aluminium electrode was used at classical performance values. At the second stage, the capacity was reduced by two and four times. At the second stage, a saturating paste containing aluminium powder was applied to the surface before the ESA. The microstructure of the obtained modified surfaces was examined under an optical microscope, the surface roughness and microhardness distribution in the surface layer were determined. Results. The use of two-stage alitization increases the microhardness of the hardened layer and the diffusion zone, as well as reduces the surface roughness. The coating integrity was 100%. (originality) A new method of alitisation based on ESA is proposed, which allows to obtain 100% continuity with high adhesion to the substrate. Рractical value. For practical implementation, it is recommended to perform alitization according to the following variant: the first stage is ESA with an aluminium electrode with a discharge energy Wp = 4.6-6.8 J, the second stage is the application of a saturation paste containing aluminium powder and graphite powder. Electrospark alloying should be carried out with a reduced productivity by about two times.

Induction Heat Treatment of a Tantalum-Containing Coating Produced on Commercial Titanium by Electrospark Alloying

Induction Heat Treatment of a Tantalum-Containing Coating Produced on Commercial Titanium by Electrospark Alloying

ОБРАБОТКА РЕЗУЛЬТАТОВ ЭКСПЕРИМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ ИСПОЛЬЗОВАНИЯ ТЕХНОЛОГИЙ КОМПЛЕКСНОГО МИКРОПЛАЗМЕННОГО УПРОЧНЕНИЯ РАБОЧИХ ОРГАНОВ И ДЕТАЛЕЙ СЕЛЬСКОХОЗЯЙСТВЕННЫХ МАШИН

Today, the problem of maintaining the efficiency of complex modern domestic and foreign agricultural machines is quite acute. The working units of agricultural tillage machines operate in an aggressive abrasive environment, which leads to their intensive wear and, as a result, to the loss of geometric shape. This, in turn, leads to a violation of agrotechnical requirements, which significantly affects the yield of cultivated crops. Serial working units of soil-cultivating machines are made of alloy steels of the ST65G type with a working hardness of HRC 55 ... 60. The purpose of the research is to increase the wear resistance of the working bodies of tillage agricultural machines by using the technology of complex microplasma hardening, with the development of a methodology for determining rational modes of processing working surfaces. To evaluate the effectiveness of complex hardening of laboratory samples, studies of the elemental composition of the hardened layer were carried out. Plates made of ST65G steel were used as laboratory samples. Hardening was carried out using various combinations of cermet powders and microplasma hardening modes. Determination of wear resistance was carried out on a friction machine 77 MT-1. The best results were noted after vibro-arc hardening followed by electrospark alloying and the use of a cermet powder consisting of 80% PG-10N-01 matrix powder and 20% B4C boron carbide. Based on the indicators of hardening regimes, Lagrange interpolation polynomials were constructed, which describe the dependence of the amount of sample wear on the current and voltage, an algorithm was developed for determining rational hardening regimes to achieve maximum wear resistance of the studied samples. The microhardness of the surface of products during electrospark hardening increased up to 2 times, and with vibroarc in combination with electrospark alloying and the use of special pastes with cermet powders - more than 3 times. The depth of the hardened surface layer with complex hardening is about 0.3 mm.

Исследование износостойких покрытий, нанесенных на образцы из конструкционной стали, применяемой для изготовления валов валопровода судов на подводных крыльях

Effective interaction of structural elements and materials from which they are made is one of the most important tasks in the design of parts and mechanisms of ship power plants. The operating experience of Meteor-type vessels has shown that the main cause of propeller shaft breakage and failure may be non-compliance with the technical requirements for the chemical-thermal processing of the shaft necks to the bearings size or poor-quality superficial coating. There has been made a comparative analysis of coating technologies, its results will significantly increase the cyclic wear resistance of the surface layer of the shaft necks of the hydrofoil ship shafting. The technologies of gas-plasma and gas-dynamic spraying, as well as electrospark alloying of the surface are considered. An instrumental assessment of the parameters of the applied protective coating quality is performed. Alloying materials for each of the methods of the surface hardening and modification are also presented. The scheme and design of the stand for testing the applied coatings for cyclic fatigue strength up to the moment of critical failure are given. The coatings deposited on the samples surfaces are studied to assess the surface microgeometry and microhardness. The samples are tested on the stand with a cyclic load at an induction motor shaft speed of 1800 rpm (30 rps). A bearing ball made of steel is used as an indenter. After testing, the focus of the coating destruction is assessed visually using a measuring and computing complex based on an optical microscope. As a result of the tests, it is revealed that the samples processed by the electrospark alloying method have the highest resistance to alternating cyclic effects, the lowest surface roughness and the highest microhardness.

Coatings Prepared by Electro-Spark Alloying with SHS Electrode Materials Based on Ti-B-Fe-AlN

In this work, the features of the phase composition, structures, and properties of coatings obtained on a high-speed steel substrate (steel R6M5) were studied. The coatings were prepared using the ESA method (electro-spark alloying). Electrode materials prepared through self-propagating high-temperature synthesis (SHS) based on (Ti-B-Fe)xAlN with the addition of nanosized AlN particles in the amount of x = 0.5, 10, 15 wt % were used as electrodes. The structure, phase composition, and physical and mechanical properties of the SHS electrode materials are reported. It was found that the coatings inherited the structure of the SHS electrode material and formed two characteristic zones for x = 0 and three zones for x = 5, 10, 15. The surface hardness of the substrate made of the high-speed steel R6M5 with the developed coatings was found to increase up to five times compared to the uncoated substrate. It was found that the wear resistance of the samples with the coating was four to six times higher than that of uncoated samples.

Nanostructuring of Metallic Surfaces by Electrospark Alloying Method

Nanostructuring of Metallic Surfaces by Electrospark Alloying Method

Transformations of the Microstructure and Phase Compositions of Titanium Alloys during Ultrasonic Impact Treatment Part III: Combination with Electrospark Alloying Applied to Additively Manufactured Ti-6Al-4V Titanium Alloy

Scanning electron microscopy, 3D optical surface profilometry, as well as X-ray diffraction and electron backscatter diffraction analysis were implemented for studying the effects of both ultrasonic impact treatment (UIT) and ultrasonic impact electrospark treatment (UIET) procedures on the microstructure, phase composition, as well as the mechanical and tribological properties of Ti-6Al-4V samples fabricated by wire-feed electron beam additive manufacturing. It was shown that he UIET procedure with the WC-6%Co striker enabled to deposit the ~10 µm thick coating, which consists of fine grains of both tungsten and titanium-tungsten carbides, as well as titanium oxide. For the UIET process, the effect of shielding gas on the studied parameters was demonstrated. It was found that the UIET procedure in argon resulted in the formation of a dense, continuous and thick (~20 µm) coating. After the UIET procedures in air and argon, the microhardness levels were 26 and 16 GPa, respectively. After tribological tests, wear track surfaces were examined on the as-built sample, as well as the ones subjected to the UIT and UIET procedures. It was shown that the coating formed during UIET in air had twice the wear resistance compared to the coating formed in argon. The evidence showed that the multiple impact of a WC-Co striker with simultaneous electrical discharges was an effective way to improve wear resistance of the Ti-6Al-4V sample.

Investigation of the Lubricated Tribo-System of Modified Electrospark Coatings

This work presents the results of tribological tests of Mo and combined coatings TiAlC formed using electrospark alloying (ESA) technology and additionally processed using thermochemical electrolyte anodic heating (TEAH). ESA makes it possible to form 15–20 µm thick coatings on the friction surface, characterized by a high hardness and wear resistance. Tribological studies were performed by testing the block-on-roll friction pair under 300 N and 600 N loads. The duration of the tests was 180 km of friction path, and the constant rotation rate of the disk was 600 rpm. It was observed that the friction torque during the 300 N loading tests was stable for all samples and throughout the entire testing period, whereas at 600 N loading, the pair with the Mo coating had a decreasing trend, and the pair with the TiAlC coating, friction torque slightly increased. For a reference sample without the coating trend of friction torque became drastically unstable. At both loads (300 N and 600 N), the friction pair with the reference sample had the highest cumulative wear, and the pair with the Mo coating had the lowest. At both loads, the cumulative wear of the friction pair with Mo coating is about 2 times lower than the TiAlC, and ≥1.8 times lower than the control (not coated) version. This study shows that at lower loads, the friction pair formed by the TiAlC coating and steel C45 is more matched than the friction pair with Mo coating.

Improving the technology of nitridation by the electro-spark alloying method

The work shows studies aimed at developing methods for protection of structural steels on the example of steels 20 and 40, from wear, using the electricity spark alloying (ESA), by applying the nitrogen-like mixture on the treated surface with subsequent vanity of steel electrode appropriate to the material of the workpiece. To increase the thickness of the surface layer and the best adhesion of the coating is offered in front of the ESA electrode-tools made of steel of the corresponding brand, to form a mold of aluminum, using an electrode from the aluminum bar of the brand of blood pressure. Metrolographic studies were performed and the distribution of microtrandomness in the coating. Studies have shown that nitrogen -containing coatings consist of a "white" layer ", which smoothly goes into the diffusion zone and base metal. The obtained coatings have the highest thickness of "white layer" 110-130 microns. The results of the study of the micro-hardness of the obtained nitrogen-containing coatings indicate an increase in hardness to 9700-9910 MPa. The phase composition of nitrogen coatings is represented by a alloy solid and cubic iron nitride, aluminum dissolves in nitride and ferrite. The considered methods of application of nitrogen -containing coatings can be used to strengthen the surface of responsible parts and elements of pumping and compressor equipment: end surfaces of rings, for protective bushings; piston machines, mechanisms that have increased wear of the product, etc. Keywords: electro-spark alloying, microstructure, nitriding, steel, phase analysis.

Synthesis of Multicomponent Coatings by Electrospark Alloying with Powder Materials

The results of systematic studies of the electrospark alloying process with the introduction of dispersed materials into plasma of low-voltage pulsed discharges are presented. Technological methods have been developed for supplying the powder material straight into the treatment zone through a hollow electrode of an anode or from the side, with the electrode-anode periodically contacting the substrate of cathode. It has been established that under the same energy regimes, when powder materials were introduced into the discharge zone, the increase in the mass of the cathode per time unit increases from 10 to 15 times or more. This study presents the process of synthesis of carbide phases (TiC and WC) during electrospark alloying of steel substrates with electrodes made of Ti, W, and graphite, with additional supply powders of these materials into the processing zone. A process has been developed for the synthesis of ternary compounds, so-called MAX-phases: Ti2AlC, Ti2AlN and Ti3SiC2 by electrospark alloying with powder compositions TiAlC, TiAlN and TiSiC. These MAX phases exhibit a unique combination of properties that are characteristic of both metals and ceramics. Energy modes of the processing were optimized, which resulted in high-quality coatings with the maximum content of carbide phases and ternary compounds. It has been established that the energy of electrical pulses during electrospark alloying, when powders of materials are fed into the interelectrode gap, ranges from 0.8 to 3.0 J, depending on their thermal physical properties. High wear and corrosion resistant characteristics of C45 structural steel with such electrospark coatings are obtained. The wear of steel with coatings in comparison with uncoated steel decreased by an average of 5.5–6.0 times. It was estimated the high corrosion resistance of 40X13 steel coated with TiC and WC in 3% NaCl solution. The corrosion current for these coatings is 0.044 and 0.075 A/cm2, respectively, and is significantly less than for coatings made of TiAlC, TiAlN, and TiSiC compositions. X-ray phase and optical metallographic microscopy analyses enabled the display of the amorphous-crystalline nature of the coatings.

Optimization of the technology for applying discrete coatings in restoration of bronze parts by electrospark alloying

In this work, a multicriteria optimization of the technology for applying discrete coatings by electrospark alloying in the restoration of bronze parts is carried out. As criteria for optimizing the process of electrospark alloying, tribotechnical characteristics were chosen – the wear intensity and friction coefficient of the coating. As adjustable parameters, those design, technological and operational factors that have the greatest influence on the value of optimization criteria are used: coating material; lubricant; operating current; amplitude of electrode oscillations; sliding speed; specific load. As a result of experimental studies, experimental dependences of wear intensity and friction coefficient for various coating materials, sliding speeds and lubrication conditions were obtained. The use of multicriteria optimization of the electrospark alloying technology made it possible to obtain various alternative coating options and technological parameters of their application for various operating conditions. Of the studied coatings, the most effective is a two-layer coating with the first layer SP-2 and an outer layer of the base material bronze BrAZhMts 10-3-1.5, which is explained by the formation of wear-resistant areas based on Mn and Ni. Multiparametric optimization of the electrospark alloying technology made it possible to reveal a combination of structural and technological factors that ensure the formation of discrete coatings with high operational properties in the restoration of bronze parts.