Electrospark Alloying Research Articles

Increasing the corrosion resistance of turbine

The reliability of the vane apparatus of steam turbines largely determines the operation of the turbine as a whole. The results of scientific research indicate that the surface operation of the blades in the wet - steam flow is caused by a combination of corrosion and drip erosion. The presence of chemical elements and compounds in the working fluid intensifies the process of blade wear. The pH value of the working environment, which can fluctuate significantly during operation, has a significant effect on the wear characteristics. The influence of methods of strengthening the leading edges of steam turbine blades made of steel is analyzed 15Х11МФ on corrosion resistance. Corrosion tests of blade samples were carried out, the inlet edges of which were strengthened in three ways: high current amplification, electrospark alloying with T15K6 alloy, electrospark alloying with steel 15Х11МФ According to the results of the tests, the layer strengthened by hardening by high-frequency currents has the lowest corrosion rate, the layer strengthened by electrospark alloying with T15K6 hard alloy has the highest. The corrosion rate of the layer reinforced by electrospark alloying of steel 15H11MF is 2.1 less than that of the layer reinforced with T15K6 alloy.

Study of hardness and morphology of carbide coatings obtained on complex shaped steel items by electro-spark alloying

The work investigated the possibility of forming carbide coatings by electrospark alloying on steel products of complex shape. It has been established that electrospark alloying at an AC current of 1.0 to 4.5 A makes it possible to form coatings of hard carbide alloy VK6 and T15K6 characterized by microhardness up to 11.5 GPa and by hardness HRA 86.6 and 81.5 with the nitial hardness of the steel product HRA 80.3.

Особенности формирования фазового и элементного состава при электроискровом легировании ручным вибратором повышенной частоты

The phase and elemental compositions of electrospark coatings of nickel and titanium deposited on steel, nickel, and titanium, that is, coatings from TiNiMo-20 and WC92-Co8 on steel at high-frequency electrospark alloying are investigated. It is established that the material of the electrode, of the substrate, and the mode of deposition have the main impact on physical and chemical properties of the formed coatings. A positive influence of high-frequency alloying on quality indicators of the processed surfaces is shown. Both the phase and chemical analyses showed availability of the compounds considerably improving corrosion resistance of the processed surfaces. Alloying with WC92-Co8 electrodes at a high frequency makes it possible to obtain an increased content of tungsten carbide in the deposited layer.

Anode Materials for Electrospark Alloying of Aluminium-matrix Alloys

This paper describes the optimum compositions of four aluminium matrix alloys (A, B, C, D) obtained from oxides (NiO, TiO2, ZrO2, Cr2O3) by means of aluminothermy (self-propagating high-temperature synthesis, or SHS metallurgy). These compositions were developed in order to enhance the wear resistance of coatings on steel 45 during electrospark deposition. Depending on the composition of synthesized alloys, the authors obtained different combinations of the structural components — i.e. aluminides of Ni, Zr, Cr, Ti, complex alloyed solid solution and eutectic. The above structural components of the aluminium matrix alloys were identified by means of electron microscopy and electron probe microanalysis. The authors established and substantiated how the alloy composition can impact the structure and the distribution of elements (segregation). The synthesized alloys A, B, C and D were used as anode materials to enhance the wear resistance of coatings on steel 45. Rows of gain (∑Δк·10–4, g), erosion (∑Δа·10–4, g), transport coefficient (∑Кp, %) and wear factor (∑Иls·10–4, g) were obtained. For all of the above mentioned parameters, mathematical expressions were obtained for the polynomial equations of the trend showing kinetic dependencies on the electrospark deposition time when the studied anode materials were used in the process. A test of validity was also defined to analyze the resultant polynomial lines of the Rл trend showing the kinetic dependencies ∑Δк, ∑Δа, ∑Кp, ∑Иls. High wear resistance values could be observed in all cases when the anode material D was used in the electrospark deposition process – % (wt.): 33.29 Al; 41.6 Ni; 10.27 Cr; 4.6 Zr; 7.23 Ti; 2.98 Fe. The material D showed optimum values in all the studied modes. Correspondingly, the value ∑Иls increased by 3.27 times. Lower wear resistance values were obtained for the alloy A – % (wt.): 36.52 Al; 47.65 Ni; 15.83 Ti. The wear factor ∑Иls increased by 1.85 times. At the same time, the wear factor of steel 45 without coating when it was subjected to similar wear conditions was as follows: ∑И(st.45) = 72·10–4 g.The research was carried out under financial support of the RF Ministry of Science and Higher Education within the Government Order No. FEME-2020-0010 "Physical-chemical and technological base of metallothermic metal synthesis in metal alkali melts and complex alloyed nickel aluminides via SHS metallurgy". Investigations were conducted using equipment of the common use center "Applied materials science"of the Pacific National University.

Physico-Mechanical and Tribological Properties of Carbon-Containing Surface Nanocomposites Produced by Electrospark Alloying

Physico-Mechanical and Tribological Properties of Carbon-Containing Surface Nanocomposites Produced by Electrospark Alloying

Analysis of the Quality of Sulfomolybdenum Coatings Obtained by Electrospark Alloying Methods.

The authors of this paper have attempted to improve the quality of surface layers applied to steel elements of machine parts constituting friction couples. The main goal of the research was to investigate an electrospark alloying method process for obtaining abrasion-resistant tribological coatings containing molybdenum disulfide on a steel surface. A substance in the form of sulfur ointment with a sulfur content of 33.3% was applied on the surfaces of C22 and C40 steel specimens. In order to determine the influence of the energy parameters of ESA equipment on the quality parameters of coatings, the ESA process was carried out using a molybdenum electrode with discharge energies Wp = 0.13; Wp = 0.55; Wp = 3.4 J. The following tests were carried out on specimens with such coatings: metallographic analysis, microhardness tests, surface roughness, and local X-ray diffraction microanalysis. The experiments revealed that sulfomolybdenum coatings consist of four zones with different mechanical properties. Depending on the discharge energy and the substrate material, the hardness of these zones varies from approx. 1100 to over 10,000 MPa. Differences in the distribution of, among others, sulfur and molybdenum in the obtained coatings, as well as differences in the microstructure of the observed coatings, were observed.

Электроискровое упрочнение дереворежущего инструмента

Choosing effective methods and devices for surface hardening of wood-cutting tools is problematic due to the variety of their designs and operating conditions. In this regard, the development of such devices becomes an urgent task. According to the literature, one of the effective methods for increasing the service life of machine parts and tools is electrospark hardening or electrospark alloying. Industrial electrospark installations such as “EFI” (electrophysical measurements) and “Elitron” with manual vibrators are used for electrospark hardening. However, using manual vibrators significantly increases the labour intensity and hardening time. Moreover, the surface quality after hardening with manual vibrators is often unsatisfactory. Various mechanized installations have been developed in order to reduce the labour intensity of electrospark hardening. Nevertheless, these installations are designed to harden specific parts and do not allow hardening tools of various designs, including woodcutting tools. The surface quality after hardening in mechanized installations does not always satisfy the customer. Further surface plastic deformation treatments, such as rolling and unrolling with rollers and balls, as well as diamond burnishing, are often used to improve the surface quality after electrospark hardening. The surface quality after additional processing by these methods boosts, although the labour intensity and cost of the hardening process increase. To increase the wear resistance of machine parts and tools, it is reasonable to reduce the height parameters of roughness, increase microhardness, and form the residual compressive stresses, which is ensured by the methods of surface plastic deformation. In this regard, it becomes necessary to use electrospark hardening simultaneously with surface plastic deformation. The work presents the design and features of using the device for hardening. The device was used to strengthen the thicknesser machine knives, which made it possible to almost double their durability. Applying this device, in comparison with using the electrospark hardening with a manual vibrator, reduces the roughness of the hardened surface and improves the surface quality of the processed workpieces. The modes of hardening have been installed, making it possible to effectively harden wood-cutting tools. For citation: Buglaev A.M. Device for Wood-Cutting Tool Hardening. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 134–141. DOI: 10.37482/0536-1036-2021-5-134-141

Increasing the life of the center plate-center bowl friction unit of a freight car by applying a combined coating formed by electrospark alloying

An increase in the operational reliability of friction units of railway transport by applying antifriction combined coatings formed by electrospark alloying, which ensures their greater strength and adhesion to metal, is considered. Keywords: electrospark alloying combined antifriction coating, strength, adhesion. alekc_sap@mail.ru

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.

Anode materials for ESA from complex-alloyed aluminium matrix alloys synthesized from oxide compounds by SHS metallurgy

The research results of influence of zirconium in anode Al – Ni – Zr alloys on character of elements distribution on section of the coating obtained by electrospark alloying (ESA) at the following modes of processing: tsk = 50, tp = 40 microseconds; tsk = 25, tp = 80 microseconds (hereinafter – mode 50/40 and mode 25/80, respectively) are presented. With the 50/40 mode, a large number of alloying elements and a smaller amount of harmful impurities of iron and manganese are concentrated in the alloyed coatings. Therefore, the reinforcing phases Al2Ni or Al2(Ni,Zr), representing solid solutions of Ni or Ni, Zr in the nickel aluminide AlNi – β’ -phase, crystallize in a large volume in the structure of coatings. With the 25/80 mode, the structure consisting of the β’ -phase and Al3Fe is formed in the coatings using the AlNi electrode and zirconium-containing Al – Ni – Zr. With the 50/40 mode, the structure consisting of a β’ -phase and a triple chemical compound β(Al – S – Fe) of unknown stoichiometric ratio is formed in this layer. Regularities of distribution of elements (Al, Ni, Fe, Si, Zr, Mn) on coatings section depending on the content of zirconium in anode Al – Ni – Zr alloys are established:– the iron and aluminum content in coatings varies according to the extreme scheme depending on the concentration of zirconium in anode alloys with a minimum value of aluminum and a maximum value of iron concentration at 1.05% (wt.) Zr;– the content of silicon and zirconium constantly increases as the zirconium concentration in electrode materials increases to 3.52% (wt.) Zr;– the content of zirconium in electrodes has almost no effect on the concentration of manganese in coatings;– with the processing mode 25/80 the nickel content decreases, and with the processing mode 50/40, on the contrary, increases to 3,52% (wt.) Zr.The 50/40 mode is the most efficient, since at a content of 3.52% (wt.) Zr in the electrode alloy there is a greater number of reinforcing zirconium-containing nickel aluminides.The work was performed with the financial support of the Ministry of Education and Science of the Russian Federation within the framework of GZ No. FEME-2020-0010 “Physico-chemical and technological bases of metallothermic synthesis of metals in ionic melts of alkali metals and complex-alloyed nickel aluminides by SHS-metallurgy”. The research was conducted within the framework of the R&D of the Scholarship of the President of the Russian Federation SP-1904.2019.1 (2019–2021) on the equipment of the CUC “Applied Materials Science” FSBEI HE “TOGU”.

Зміни в структурі стопу Co–15%W після електроіскрового леґування та відпалу

Зміни в структурі стопу Co–15%W після електроіскрового леґування та відпалу

Electrospark alloying of titanium alloy aircraft engine parts

The study objective is to improve the performance of titanium alloy parts used in aircraft jet engines with electrospark alloying. The technology can be used for hardening compressor rotary vanes and rod ball joints, protecting compressor blade leading edges from erosion. We studied the alloyed layer formation process and determined the layer structure and composition. The study presents experimental findings of the Ti alloy electrospark alloying as certain substances were introduced into the interelectrode gap. We also assessed the relationship between the electrospark alloying process variables and the alloyed layer surface finish.

THE STRUCTURE OF ELECTROSPARK NANOCOMPOSITE COATINGS ON A METAL MATRIX

Electrospark alloying (ESA) of conducting surfaces of solids is a promising direction for increasing the operational properties of materials at the present time. The formation of coatings of superhard materials on a substrate can significantly increase the hardness, wear resistance, resistance to high temperatures and pressure. This article investigates the chemical composition, structure, physical and mechanical characteristics, morphology of coatings formed on metal substrates. It was found that the technological parameters of the formation of electrospark coatings have a significant effect on the morphology, structure, and physical and mechanical characteristics of the modified materials. The structure of the protective layers depends significantly on the chemical composition of the electrodes. MAX phases are formed in ESA coatings.     &nbsp

CORROSION RESISTANCE OF REINFORCED LAYERS OF 15Х11МФ STEEL STEAM TURBINE BLADES

The reliability of the vane apparatus of steam turbines largely determines the operation of the turbine as a whole. The results of scientific research indicate that the surface operation of the blades in the wet-steam flow is caused by a combination of corrosion and drip erosion. The presence of chemical elements and compounds in the working fluid intensifies the process of blade wear. The pH value of the working environment, which can fluctuate significantly during operation, has a significant effect on the wear characteristics. The influence of methods of strengthening the leading edges of steam turbine blades made of steel is analyzed 15H11MF on corrosion resistance. Corrosion tests of blade samples were carried out, the inlet edges of which were strengthened in three ways: high current amplification, electrospark alloying with T15K6 alloy, electrospark alloying with steel 15H11MF. According to the results of the tests, the layer strengthened by hardening by high-frequency currents has the lowest corrosion rate, the layer strengthened by electrospark alloying with T15K6 hard alloy has the highest. The corrosion rate of the layer reinforced by electrospark alloying of steel 15H11MF is 2.1 less than that of the layer reinforced with T15K6 alloy.

Improving Ecological Safety when Forming Wear-Resistant Coatings on the Surfaces of Rotation Body Parts of 12Kh18N10T Steel Using a Combined Technology Based on Electrospark Alloying

Improving Ecological Safety when Forming Wear-Resistant Coatings on the Surfaces of Rotation Body Parts of 12Kh18N10T Steel Using a Combined Technology Based on Electrospark Alloying

Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method.

In this paper, the possibility of applying the electrospark alloying (ESA) method to obtain boron-containing coatings characterised by increased hardness and wear resistance is considered. A new method for producing such coatings is proposed. The method consists in applying grease containing aluminium powder and amorphous boron to the surface to be treated and subsequently processing the obtained surface using the ESA method by a graphite electrode. The microstructural analysis of the Al-C-B coatings on steel C40 showed that the surface layer consists of several zones, the number and parameters of which are determined by the energy conditions of the ESA process. Durametric studies showed that with an increase in the discharge energy influence, the microhardness values of both the upper strengthened layer and the diffusion zone increased to Wp = 0.13 J, Hµ = 6487 MPa, and Wp = 4.9 J, Hµ = 12350 MPa, respectively. The results of X-ray diffraction analysis indicate that at the discharge energies of 0.13 and 0.55 J, the phase composition of the coating is represented by solid solutions of body-centred cubic lattice (BCC) and face-centred cubic lattice (FCC). The coatings obtained at Wp = 4.9 J were characterised by the presence of intermetallics Fe4Al13 and borocementite Fe3 (CB) in addition to the solid solutions. The X-ray spectral analysis of the obtained coatings indicated that during the electrospark alloying process, the surface layers were saturated with aluminium, boron, and carbon. With increasing discharge energy, the diffusion zone increases; during the ESA process with the use of the discharge energy of 0.13 J for steel C40, the diffusion zone is 10–15 μm. When replacing a substrate made of steel C40 with the same one material but of steel C22, an increase in the thickness of the surface layer accompanied by a slight decrease in microhardness is observed as a result of processing with the use of the ESA method. There were simulated phase portraits of the Al-C-B coatings. It is shown that near the stationary points in the phase portraits, one can see either a slowing down of the evolution or a spiral twisting of the diffusion-process particle.

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.

Mathematical modeling of the process of hardening treatment of titanium alloys VT20 and OT4

Mathematical models have been developed for the surface hardening of VT20 and OT4 titanium alloys by electrospark alloying, which can be used in the design of technological processes for the manufacture of titanium blades of steam turbines.

The mathematical modeling of the process of hardening treatment of titanium blades of steam turbines

Mathematical models of the surface hardening of VT20 and OT4 titanium alloys by electrospark alloying have been developed. These models can be used in the design of technological processes for the manufacture of titanium blades for steam turbines.

Improving the performance of gas turbine engine blades based on functionally oriented coatings

Mathematical models have been developed for the surface hardening of VT20 and OT4 titanium alloys by electrospark alloying, which can be used in the design of technological processes for the manufacture of titanium blades of steam turbines.