Electrospark Deposition Research Articles

High-entropy Fe–Co–Cr–Ni–(Cu) coatings with enhanced corrosion and tribocorrosion resistance obtained by vacuum electrospark deposition

High-entropy Fe–Co–Cr–Ni–(Cu) coatings with enhanced corrosion and tribocorrosion resistance obtained by vacuum electrospark deposition

Effect of TaC content on microstructure and wear behavior of PRMMC Fe-TaC coating manufactured by electrospark deposition on AISI304 stainless steel

The Fe-TaC coatings on stainless steel by electrospark granule deposition in an anode mixture of iron granules and tantalum carbide powder were first obtained. The material deposition rate on the substrate increased with the TaC powder concentration growth in the anode mixture, facilitating the initiation of electrical discharges. X-ray analysis of deposited coatings shows the presence of the TaC, γFe, and αFe phases. The tantalum carbide concentration grows with an increase in the content of TaC powder in the anode mixture, from 2.4 to 14.8 vol%. The dependence of the wear rate of coatings on the concentration of tantalum carbide in the anode mixture had a parabola form, with a minimum of 5 vol%. However, with a further increase in the TaC concentration in the anode mixture, the wear rate of the coatings monotonically increased due to spalling of TaC grains due to a deficiency of the metal binder.

In-situ CrFeCoNi medium entropy alloying coating via electrospark powder deposition

Medium or high-entropy alloys have led to widespread interest in their preparation, property control, and applications. The ability to apply these new alloys as coatings on conventional materials allows alternative surface treatment methods. This study used electrospark deposition with powder feedstock, to form MEA coating with fine-tuned compositions on steel substrate. Single-phase CrFeCoNi MEA using optimized ESD parameters and powder formulation. The phase and composition of MEA coatings and their hardness were also characterized. The coating showed two orders of magnitude reduction in specific wear rate coefficient compared with that of bare A516 steel substrate. This study demonstrates that the powder-based ESD technique can be used to create in-situ M/HEA coatings for applications requiring improved properties.

Износостойкость и коррозионное поведение Cu-Ti-покрытий в растворе SBF

Introduction. Currently, titanium and its alloys have become the most popular metal implantable biomaterials. However, the main disadvantage of titanium alloys is low wear resistance due to high viscosity. It is known that copper-titanium coatings effectively improve the antibacterial properties of titanium alloy and at the same time increase its wear resistance. Purpose of the work is to study the effects of a solution simulating body fluid on corrosion properties, friction coefficient and the wear of copper-titanium coatings obtained by electrospark deposition method of the Ti-6Al-4V alloy. Method. A non-localized electrode consisting of copper and titanium granules in various ratios was used to form copper-titanium coatings on a titanium alloy by electrospark deposition. The structure of the coatings was examined using a DRON-7 X-ray diffractometer in Cu-Kα radiation and an X-max 80 energy dispersive spectrometer. The antibacterial activity of the deposited Cu-Ti coatings was studied on a non-pathogenic gram-negative culture of Escherichia coli. Polarization tests in SBF solution were carried out using a P-40X potentiostat with an impedance measurement module. The metal content in the SBF solution after immersion of the samples was measured using an ICP-MS 2000 mass spectrometer. The tribological characteristics of the coatings according to the ASTM G99-17 standard using the “ball-on-disk” scheme with sliding friction in the SBF solution at loads of 10 and 25 N were examined. Results and discussions. It is shown that the bactericidal activity of Cu-Ti coated samples to a non-pathogenic culture of Escherichia coli increased monotonously with an increase in copper content. With copper concentration increasing, the corrosion current density of the coatings increased from 3.455 to 17.570 μA/cm2. It is shown that the SBF solution accelerates the wear of a titanium alloy many times over due to its interaction with the electrolyte via the oxidative wear mechanism. The use of Cu-Ti coatings allows reducing the friction coefficient and greatly decreasing the wear of Ti-6Al-4V alloy in the presence of an electrolyte.

Electrospark Deposition of Hard, Wear-Resistant and Anti-Friction Tribological Coatings on γ-TiAl Substrates in a Controlled Gas Environment

Electrospark Deposition of Hard, Wear-Resistant and Anti-Friction Tribological Coatings on γ-TiAl Substrates in a Controlled Gas Environment

Study on the Properties of TiC Coating Deposited by Spark Discharge on the Surface of AlFeCoCrNiCu High-Entropy Alloy.

Titanium carbide (TiC) coatings were prepared on the surface of AlFeCoCrNiCu high-entropy alloy blocks using electro-spark deposition (ESD). The microhardness and corrosion resistance of the TiC coatings prepared under different voltage and capacitance process parameters were studied. The research shows that the maximum microhardness of the TiC coating on sample 4 (working voltage of 20 V, working capacitance of 1000 μF) is 844.98 HV, which is 81.5% higher than the microhardness of the substrate. This is because the deposition energy increases with the increase in voltage, and the adhesion and aggregation between the coating and the substrate are enhanced, increasing the hardness of the coating. It is worth noting that excessive deposition energy can increase surface defects and reduce the microhardness of the coating surface. Electrochemical testing analysis shows that the corrosion current density of the TiC coating is the lowest (9.475 × 10-7 ± 0.06 × 10-7), and the coating impedance is the highest (2.502 × 103 Ω·com2). The absolute phase angle value is the highest (about 72°). The above indicates that the TiC coating prepared with a working voltage of 20 V and a working capacitance of 1000 μF has better microhardness and corrosion resistance.

Protective Heterophase Coatings Produced by Electrospark Deposition and High-Power Impulse Magnetron Sputtering

Protective Heterophase Coatings Produced by Electrospark Deposition and High-Power Impulse Magnetron Sputtering

Fabrication of high speed steel electrodes with MoSi2–MoB–HfB2 ceramic additives for electrospark deposition on die steel

The electrodes for electrospark deposition (ESD) were fabricated from hot-pressed blanks composed of a mechanically alloyed powder mixture of R6M5K5 high speed steel. This mixture was enriched with a 40 % addition of heat-resistant MoSi2–MoB–HfB2 ceramics, produces through the self-propagating high-temperature synthesis method (resulting in the R6M5K5-K electrode), as well as variant without any ceramic addition (resulting in the R6M5K5 electrode). We examined both the composition and structure of the electrode materials and the coatings derived from them, identifying the characteristics of mass transfer from hot-pressed electrodes to substrates of 5KhNM die steel under various frequencies and energy conditions during processing. The R6M5K5 electrode consists of an α-Fe-based matrix incorporating dissolved alloying elements and contains discrete particles of ferrovanadium, tungsten carbide, and molybdenum. The R6M5K5-K electrode, in addition to the α-Fe-based matrix, includes borides and carbides, as well as hafnium oxide. The use of the R6M5K5 electrode resulted in a consistent weight increase in the cathode throughout the entire 10-minute processing period. In contrast, the application of the ceramicenhanced electrode led to weight gain only during the initial 3 min of processing. Subsequently, ESD produced coatings of 22 and 50 μm thickness on the surface of 5KhNM steel using R6M5K5 and R6M5K5-K electrodes, respectively. The introduction of SHS ceramics escalated the roughness (Ra) of the surface layers from 6 to 13 μm and the hardness from 9.1 to 15.8 GPa. The coating from the R6M5K5 electrode was composed of austenite (γ-Fe) and exhibited high uniformity. Conversely, the coating from the R6M5K5-K electrode consisted of a diverse matrix with both crystalline and amorphous iron, an amorphous phase rooted in the Fe–B alloy, and scattered phases of HfO2, HfSiO4, Fe3Si, and Fe3B. High-temperature tribological testing at 500 °C in an air atmosphere showed that the coatings possess a friction coefficient of 0.55–0.57 when coupled with a counterbody of AISI 440C steel. The integration of heat-resistant ceramics notably enhanced the coating's wear resistance, increasing it by a factor of 13.5.

Surface functionalization of binder jetted steels through super-solidus liquid phase sintering and electro-spark deposition

This study proposed a surface functionalization strategy for porous binder jet additive manufacturing (BJAM) steels. The methodology involves a sequential process of super-solidus liquid phase sintering (SLPS) followed by electro-spark deposition (ESD). SLPS with varying liquid fractions was used to modify the initial surface quality of BJAM steels, creating a range of surface roughness and bulk porosity. The ability of ESD to address substrate surface roughness and porosity variation was investigated using lower (Inconel 625) and higher (WC-Co) melting point coating materials. The results revealed a clear correlation between substrate surfaces and the surface finish, uniformity, and thickness of ESD deposits. Inconel 625, with its lower melting point, showcased an infiltration behavior and high tolerance to substrate conditions. Conversely, achieving high-quality WC-Co coating necessitated prior SLPS treatment to attain substrates with minimal roughness and sub-surface porosity. This investigation provides insights into optimizing surface modifications for porous BJAM metal parts, considering different coating materials and their compatibility with substrate conditions.

Features of Electrospark Coatings Formation on a Chromium Substrate Using Ceramic ZrSi2-MoSi2-ZrB2 and HfSi2-MoSi2-HfB2 Electrodes

The work is devoted to the study of the features of mass transfer, structure and properties of electrospark coatings on substrates made of the chromium alloy grade VKh1-17A using SHS-electrode ceramics of the compositions ZrSi2-MoSi2-ZrB2 and HfSi2-MoSi2-HfB2. The coatings were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive analysis, and tribological tests using the “pin-on-disk”; nanoindentation was also carried out. The kinetics of the mass transfer and heat resistance of coatings were determined by the gravimetric method. In accordance with the Palatnik criterion, the formation of coatings occured in the form of an alloy of an anode (electrode) and a cathode (substrate) materials, which ensures high adhesion of the surface layer. The maximum weight gain on the cathode was observed after the first minute of treatment, and subsequently a decrease in the mass of the cathode was noted. As a result of electrospark deposition, coatings with 100% continuity and a thickness of 10–20 µm were deposited on the surface of the chrome alloy VKh1-17A. Zirconium-containing coatings are characterized by a hardness of 18.2 GPa and an elastic modulus of 274 GPa, and coatings obtained using the HfSi2-MoSi2-HfB2 electrode were characterized by a hardness of 16.9 GPa and an elastic modulus of 332 GPa. The use of SHS-electrodes made it possible to increase the hardness of the surface layer of the chromium alloy by 4 times, wear resistance by 1.5 times, and oxidation resistance by 1.6 times at t 1000 °C for 30 hours of testing.

Wear-Resistant Coatings Produced from TiN–TiB2 and TiN–Si3N4 Composites by Electrospark Deposition and Laser Processing

Wear-Resistant Coatings Produced from TiN–TiB2 and TiN–Si3N4 Composites by Electrospark Deposition and Laser Processing

Protective Heterophase Coatings Produced by Pulsed Electrospark Depostioin and High Power Impulse Magnetron Sputtering

In order to increase the service life of critical products made of refractory metals, the most effective is the use of protective coatings based on oxidation-resistant ceramic materials. Using an electrode/target made of heterophase HfSi2-MoSi2-HfB2 ceramics by electrospark deposition (ESD), high-power impulse magnetron sputtering (HIPIMS) technologies, as well as the combined ESD+HIPIMS technology, coatings were deposited onto molybdenum substrate (MCh-1 brand). Electrode materials and coatings were studied by the X-ray diffraction, the glow discharge optical emission spectroscopy, the X-ray spectral microanalysis, and the scanning electron microscopy. Combined ESD+HIPIMS technology made it possible to create a hard layer of oxidation-resistant ceramics on the surface of the substrate, which does not produce through cracks inherent in ESD coatings.

Construction of wear resistant superhydrophobic structure without degrading the surface mechanical properties of alloy layer

The vulnerability of superhydrophobic surface structures frequently leads to a loss of their superhydrophobicity under friction, significantly restricting their broad-scale applicability. The preparation of alloy layers emerges as an effective strategy to enhance the mechanical properties of metal surfaces. The construction of superhydrophobic structures without loss of mechanical properties of alloy layer is expected to lead to the preparation of superhydrophobic surface with excellent wear resistance. In this study, a superhydrophobic surface with excellent hardness and wear resistance was successfully prepared by a two-step process of electrospark deposition and anodization. The superhydrophobic surface maintained superhydrophobicity under long distance friction. Firstly, alloy layer with micron bulges and excellent mechanical properties was constructed on the metal surface by electrospark deposition, which was then slightly anodized to create hierarchical micro-nano bulges rather favourable to superhydrophobicity, and anodization did not degrade mechanical properties of the surface. The surface is provided with excellent superhydrophobicity after modification with fluorosilane. SEM, 3D profilometer and roughness tester were adopted to explore microscopic morphology of the sample surfaces. XPS and FTIR were used to explore chemical components of the sample surfaces. The element distribution of the sample surfaces was analysed through EDS, and wettability of the sample surfaces was explored through the contact angle test. The hardness test and wear test were applied to explore mechanical properties of the sample surfaces. It was proved through linear friction, droplet impact, hammering and knife scratch that the superhydrophobic surface could maintain good superhydrophobicity under multiple forms of mechanical destruction, while the neutral salt spray test, electrochemical tests and acid and alkali soaking test proved the excellent property of corrosion resistance of the superhydrophobic surface. In addition, the prepared superhydrophobic surface also features an excellent self-cleaning property.

Study of the Influence of Coating Roughness on the Properties and Wear Resistance of Electrospark Deposited Ti6Al4V Titanium Alloy

The present work is concerned with studying surface parameters of coatings deposited to titanium alloy Ti6Al4V by electrospark deposition (ESD) with hard alloy depositing electrodes based on WC, TiC and TiCN. The variation of roughness parameters, composition, structure and tribological characteristics of coatings as a function of ESD mode parameters was investigated. The influence of the mode parameters on the main coating roughness parameters (Ra, Rz, Rmax, Rpk, Rk, Rs, Rsk, Rku (ISO 21920-2:2021) was analysed, the values of which can be used to determine the load bearing capacity and wear resistance. The results of the tribological tests showed that within the test range, the roughness of the coatings has a controversial influence on their frictional wear performance. As the roughness parameters increase to Ra=3÷3.5 µm, the relative wear resistance of the coated surfaces also increases, reaching values up to 4÷5 µm for the electrodes used and no significant changes in the wear mechanism were observed. However, increasing coating roughness above Ra=3.5 to 5 µm results in a monotonic decrease in relative wear resistance to 2.5÷3 times. Possible ways to reduce the surface roughness and increase the wear resistance of coatings were presented.

Electrospark Deposition of Ti – Al – Cr – B Coatings on Titanium Alloy VT3-1

Electrospark Deposition of Ti – Al – Cr – B Coatings on Titanium Alloy VT3-1

FRICTION AND WEAR PERFORMANCE OF AN ELECTROSPARK-DEPOSITED Ta COATING ON CrNi3MoVA ST

A Ta coating was prepared on a CrNi3MoVA steel substrate by means of electrospark deposition (ESD) and its friction and wear performance was investigated. The nanomechanical properties and friction coefficient were tested by employing a nanoindenter and a friction and wear testing machine, respectively. Moreover, the phase structure was obtained using X-ray diffraction (XRD), and the morphology and composition were analysed before and after friction utilizing scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the gradient Ta coating with nanocrystals is composed of -Ta and Fe-Ta intermetallics, and Ta2O5 and -Fe phases. The hardness of the Ta coating increased by 115 % compared to that of the CrNi3MoVA steel and its elasticity was reduced by 21 %. The friction coefficient of the Ta coating was reduced by 81 % compared to that of the CrNi3MoVA steel and its weight loss was reduced by 89 %. The wear mechanism of the Ta coating can be characterized as slight adherence, whilst that of the CrNi3MoVA steel includes severe adherence and fatigue.

In-situ formation of ultra-hard titanium-based composite coatings on carbon steel through electro-spark deposition in different gas media

In the current study, ultra-hard TiC, TiN, and Ti(C,N) layers were in-situ formed on carbon steel substrate using pure titanium electrode via electro-spark deposition (ESD) in argon, nitrogen, argon/nitrogen, and air atmospheres. The synthesized coatings were characterized using various techniques, including FE-SEM/EDS, X-ray diffractometry, Raman spectroscopy, microhardness and nanoindentation tests, and surface roughness measurement. Also, a thermodynamic simulation was executed to estimate the phase-stability. Fe5C2, TiN, Fe3N, and Ti2O3 were determined as the major phases formed under the argon, nitrogen, Ar/N2, and air atmospheres, respectively. The formation of martensite at the interface of the coating and substrate in all atmospheres indicates the capability of the ESD process for surface hardening. The observed discrepancies between the empirically formed phases and the thermodynamics prediction can be related to the non-equilibrium conditions of the ESD process. It was revealed that gaseous media such as argon and nitrogen serve as a protective/active environment in the titanium/steel system. It is proposed that the electro-sparking of titanium under the active nitrogen medium follows an avalanche plasma regime. Under the argon flow, FeTi intermetallic layer is formed. Whilst, electro-sparking in ambient air leads to the formation of various Fe-Ti-O compounds, as well as different TiOn oxides. On the other hand, the utilization of nitrogen gas during the ESD increases the surface roughness and the thickness of the coating, rather than the deposition under the argon flow, due to the extra heat of reactions. The dynamic reactions occur between pure titanium, nitrogen, carbon, and oxygen, leading to the initial formation of Ti(C,N) at the top surface, followed by the production of titanium oxides in the middle layer. The coexistence of the super-hard Ti(C,N) with a hardness of 3130 HV at the top surface and titanium nitrides beneath it in a gradient mode effectively impedes the crack propagation.

Improving the Surface Quality and Tribological Characteristics of 3D-Printed Titanium Parts through Reactive Electro-Spark Deposition.

This work presents the results of research conducted with an aim to improve the surface quality, hardness and wear resistance of titanium alloy Ti6Al4V, obtained via the laser powder bed fusion of metals (PBF-LB/M) process of additive manufacturing (AM) known as the 3D printing of metals. The 3D surfaces were coated via reactive electrospark deposition (RESD) with low-pulse energy and electrode materials of low-melting metals and multi-component hard alloys. The relationship between the electrical parameters of the RESD process and the quality, composition, structure, microhardness and wear resistance of the treated surfaces were investigated and analysed. It was found that the roughness and thickness of the resulting surface layers could be changed by changing the RESD modes within the limits of 2.5-5 µm and 8-20 µm, respectively. RESD processing allowed us to achieve two to five times lower roughness than that of titanium AM surfaces. The microhardness and wear resistance of the RESD surfaces are two to four times higher than those of the titanium substrate. Possibilities for the purposeful synthesis of new wear-resistant phases and compounds and for obtaining surface layers with predetermined thickness and roughness were established. It was shown that the subsequent reaction's electrospark processing helped to simultaneously reduce the roughness and increase the hardness and wear resistance of the modified surfaces, and can be successfully used instead of the material-energy-labour and machine-intensive finishing treatments of the titanium surfaces obtained after 3D printing.

Wear and corrosion behavior of TiC and WC coatings deposited on high-speed steels by electro-spark deposition

Abstract Electro-spark deposition (ESD) is one of the most effective methods for improving the surfaces of metallic materials by applying ceramic-based cermet coatings. In this study, TiC and WC coatings were deposited on the surface of AISI M2 high-speed steel using the ESD method. Subsequently, the coated surfaces were examined through microstructure, phase structure, microhardness, friction, wear, and electrochemical corrosion tests, and compared with untreated AISI M2 steel. The TiC and WC phase coatings obtained with ESD resulted in a significant improvement, with hardness levels exceeding four times that of AISI M2 steel, leading to reduced wear volume losses and friction coefficients. Furthermore, the cermet coatings formed on the surface exhibited 2–3 times improvement in corrosion resistance due to their lower conductivity. This study demonstrates that WC coatings may offer a more effective solution for enhancing the wear resistance of AISI M2 steel, while TiC coatings could be more effective in improving corrosion resistance.

Wear performance of GGG60 ductile iron rollers coated with WC-Co by electro spark deposition

Nodular cast irons are used in many industrial applications such as machine frames and body, rollers and engine blocks due to their higher strengths and ductility with good machinability comparable to grey cast irons. In this study, the outer surface of nodular cast irons (GGG-60) was coated with WC/Co using electro spark deposition (ESD). The aim of the study is to improve both the surface quality and wear behaviour with the coatings formed on the surface of the plastic deformation rollers, whose wear resistance decreases over the time due to high stress working conditions. Heat treatment at 950 ºC for 2 h was applied to the GGG60 specimen rollers and half of the rollers were uncoated and the other half was coated with WC-Co electrodes. The wear behaviour of the heat treated and coated surfaces was measured by ball-on-disc wear method using Al2O3 ball bearing with a diameter of 6 mm for a sliding distance of 250 m at a sliding rate of 6.5 m·s-1 under a dry condition, and using a load of 40 N. WC/Co coatings were successfully applied to rollers. In the SEM/EDS images, the presence of W, Fe, C, Co and Al elements in the coated part of the rollers and Fe, C and Al elements in the uncoated region were detected. It was concluded that Coating and heat treatment increased the wear resistance by nearly 5 times and decreased the friction coefficient by 2.13 times.