Chromium Powder Research Articles

Corrosion Behavior of Cobalt–Chromium‐Based Laser Claddings Reinforced with Boron Nitride, Graphene Oxide, and Graphite.

In this article, the corrosion resistance of a cobalt–chromium‐based laser cladding reinforced with different microparticles: boron nitride, graphene oxide, and graphite, added for increased tribological performance, is explored. Samples are fabricated by premixing cobalt–chromium powder with microparticle additions and cladding onto 316L stainless steel base metal. The corrosion behavior is measured in industrially relevant applications: 1 m acetic acid and 3.5 wt% NaCl, using open‐circuit potential, electrochemical impedance spectroscopy, linear polarization resistance, and cyclic polarization. Laser ablation–inductively coupled plasma–mass spectrometry is used to analyze the distribution of the chemical elements throughout the coatings. The reference cladding's corrosion resistance is outstanding in both electrolytes, with a corrosion rate (CR) of ≤0.19 μm year−1 and no pitting tendencies. With the addition of microparticles, the claddings maintain their remarkable pitting resistance, but show an increase in CR up to 0.98 μm year−1 due to the nonuniform distribution of the microparticles into the matrix.

Thermally Sprayed Coatings for the Protection of Industrial Fan Blades.

This paper presents a study on thermally sprayed coatings. Coatings produced by high-velocity oxygen-fuel spraying HVOF and plasma spraying deposited on the A03590 aluminum casting alloy are tested. The subject of this research concerns coatings based on tungsten carbide WC, chromium carbide Cr3C2, composite coatings NiCrSiB + 2.5%Fe + 2.5%Cr, mixtures of tungsten and chromium powders WC-CrC-Ni, mixtures of carbide powders with the Cr3C2-NiCr + the composite 5% NiCrBSi and WC-Co + 5% NiCrBSi. The aim of this research is to find a coating most resistant to the erosive impact of particles contained in the medium centrifuged by industrial rotors. The suitability of the coating is determined by its high level of microhardness. The hardest coatings are selected from the coatings tested and subjected to abrasion tests against a sand particle impact jet and the centrifugation of a medium with corundum particles. It is found that the most favorable anti-erosion properties are demonstrated by a coating composed of a mixture of tungsten carbide and chromium carbide WC-CrC-Ni powders. It is concluded that the greatest resistance of this coating to the erosive impact of the particle jet results from the synergistic enhancement of the most favorable features of both cermets.

Effect of sintering temperature, additive ratios, and reinforcement of boron and boron carbide particle sizes on the mechanical and tribological properties of the synthesized Cu-Cr hybrid composites

In this study, hybrid composites were generated by combining Copper (Cu) powder with Chromium (Cr) powder at a fixed weight of 1 %, as well as Boron (B) and Boron carbide (B4C) powders at specific weight ratios (1 %, 2 %, 3 %, and 4 %), with variable particle sizes (1 µm and 44 µm). Powder metallurgy production parameters were employed to produce two sets of samples at sintering temperatures of 750 °C and 850 °C. Analysis of the microstructure of the samples was performed, as well as hardness and abrasion tests. A variety of B/B4C ratios and particle diameters were employed to characterize Cu-based hybrid composites using SEM-EDS and XRD. Weight loss graphs and coefficient of friction values were generated for each sample subsequent to wear tests. The results of the tests indicated a 76.25 % increase in hardness values with B reinforcement and a 60.71 % increase with B4C reinforcement in comparison to a pure Cu sample. As the sintering temperature increased and the size of the reinforcement particles decreased, the hardness of the material increased, resulting in identical results in the wear testing. A tribo-layer was observed to have formed between the wear pin and the samples in the new hybrid composites with Boron matrix in the SEM images taken after wear. The wear resistance properties of Cu matrix hybrid composites were found to be enhanced by this tribolayer.

Tribological behavior and characteristics of TIG surface cladded AlCoCrFeNi high-entropy alloy on 304L stainless steel

The present study examines the tribological properties of AlCoCrFeNi high-entropy alloy (HEA) surface cladded on 304L stainless steel via a Tungsten Inert Gas (TIG) heat source. Commercially pure powders of aluminum, cobalt, chromium, and nickel were ball-milled, mixed in specific ratios, and applied onto the substrate with polyvinyl alcohol as a binder. Cladding was performed with optimized parameters to create layers of HEA. Microstructural and EDS analysis revealed equiaxial dendrites rich in aluminum and nickel in dendritic (DI) areas, and rich in iron, chromium, and cobalt in interdendritic (ID) areas. Mixing entropy was calculated by consideration of EDS analysis of the cladding and based on the initial definition of a high-entropy alloy, the high-entropy nature of the cladding was confirmed. XRD analysis showed the presence of FCC, A2/B2, and hard σ phases. Surface alloyed material exhibited higher hardness compared to the base material, with an average of 540 HV versus 200 HV. A pin-on-disc wear test machine was used to assess tribological properties under different loads of 10, 20, and 40 N. The wear rates of the high-entropy cladded material were 36 and 50 % less than those of the 304L stainless steel under applied loads of 10 and 40 N, respectively, while their wear rates were almost similar at 20 N. Friction coefficients of HEA pins were notably lower than 304L at 10 and 20 N, with smoother profiles. Wear mechanisms of the HEA material varied with load: oxidative wear at 10 and 20 N due to the formation of an oxide layer, and abrasion and spallation at 40 N, resulting in a threefold increase in wear rate at this load. Overall, the study highlights the effectiveness of HEA cladding in improving tribological properties, especially under high applied load.

Microstructural Evolution and Wear Resistance of Surface Alloyed AISI 316L Stainless Steel with Equi-atomic CoCrFeMnTi by Continuous Wave Diode Laser

In this investigation, a multicomponent alloyed surface was developed on AISI 316L stainless steel (AISI 316L SS) substrate by melting it with a fiber coupled diode laser having 3.6 mm beam diameter (using argon as shrouding gas) along with simultaneous melting of equiatomic pre-mixed elemental powders of cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn) and titanium (Ti) (high entropy alloy). The process parameters used in the experiment were laser power (1800–2200 W) and scan speed (6 mm/sec to 8 mm/sec). Following laser surface alloying (LSA) a detailed microstructural characterization of the surface and evaluation of surface mechanical properties (micro/nano hardness, Young’s modulus and wear resistance) were undertaken. Due to LSA there is formation of near eutectic microstructure consisting of FCC and BCC phase mixtures along with the precipitates of Fe2Ti randomly distributed in the microstructure which was confirmed by X-ray diffraction (XRD) and electron back scattered diffraction (EBSD) analysis. There is an increase in microhardness in the processed zone from 180 VHN (of as received AISI 316L SS) to 309–650 VHN. In addition, there is an increase in Young’s modulus from 208 GPa for as received AISI 316L SS to 228–301 GPa for laser surface alloyed zone. The wear resistance (against WC ball in fretting wear mode) property of AISI 316L SS substrate after LSA was superior to the substrate. The wear mechanism was established.

Manufacturing of High Purity Cr2AlC MAX Phase Material and Its Characterization

AbstractPresent study discusses about a technique for producing high-purity Cr2AlC MAX phase materials and gaining insight into their thermal behavior for high-temperature applications. The research conducted involved synthesizing a pure layered ternary carbide Cr2AlC MAX phase material by mixing powders of Chromium, Aluminum, and Carbon and then subjecting them to two-step pressureless sintering process in argon atmosphere. First step involves the annealing of ball-milled mixture at 750 °C for 2 h followed by the second step in which the annealed mixture is subjected to heat-treatment at 1350 °C for 2 h. Analysis using XRD and Raman techniques revealed that the synthesized product consists of Cr2AlC phase, without any impurities. SEM studies confirmed that the Cr2AlC had a layered topography, while EPMA analysis indicated that the atomic percentage of Cr, Al, and C was consistent with the XRD phase analysis. XPS investigations confirmed the presence of Cr-C bonds representing Mn+1Xn of the MAX phase material. TG-DSC results showed an approximately 2% increase in weight. The Cr2AlC phase exhibited an endothermic pattern below 725 °C, an exothermic pattern above it, and did not decompose up to 1400 °C in vacuum environment. High-temperature XRD analysis at various temperatures also confirmed no formation of Al2O3 or CrO impurity compounds.

Mechanochemical synthesis, purification, and optimization studies of Cr boride@MgO particles

Chromium boride, an advanced ceramic material, is commonly produced by powder metallurgy methods using elemental boron and chromium powder, borothermic reactions, or boron carbide reduction of Cr2O3. In this study, a mechanochemical method for the production of chromium boride was developed, subsequent purification was performed, and the whole process was optimized. The amounts of Cr2O3, B2O3, and Mg in the initial powder blends were determined by computational thermodynamic methods based on their equilibrium compositions. Firstly, stoichiometric starting-powder blends were milled at different durations (1, 2, 3, 4, 5, and 8 h). The optimum purification route was determined using acid leaching experiments carried out with different acids, at different temperatures, and concentrations. Secondly, powders prepared in excess amounts were synthesized at the optimum duration (5 h) and leaching condition (0.1 M HCl, 25 °C). For the 100 wt % excess B2O3, 25 wt % excess Mg and 0.8 moles of Cr2O3 composition, annealing was conducted at 1100 °C. Characterization studies, X-ray diffractometry (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and atomic absorption spectroscopy (AAS) were conducted on the milled and leached powders. After annealing, CrB, CrB2, Cr3B4 and MgO phases were obtained in the XRD patterns. The particle sizes of the resulting materials were also analyzed, and it was found to be nearly 3.11 μm after annealing. Finally, the TEM analysis revealed that the MgO peak evident in the XRD patterns was MgO shell covering the Cr boride particles having submicron sizes; hence, a pure Cr boride@MgO core-shell structure was obtained.

Optimization of conditions for the formation of functional coatings based on carboxymethylcellulose with chromium

The possibility of increasing the strength and improving the functional properties of coatings based on biopolymers by adding metal powders is considered. An approach has been proposed that makes it possible to form composites based on carboxymethylcellulose with specified mechanical properties. The procedure for adjusting the process of formation and increasing the strength of a protective coating based on carboxymethylcellulose with chromium powder is shown. For the numerical calculation of the composition and temperature conditions for the manufacture of composite materials, a software module developed in the Microsoft Visual Studio environment was used. The calculation makes it possible to determine the combination of components of the coating composition that provides the highest mechanical strength for a given value of the relative deformation of the biocomposite. An example of calculation is given for a protective coating based on carboxymethylcellulose with chromium powder. The calculation results were confirmed experimentally. Using the proposed approach makes it possible to increase the mechanical strength of coatings by 40% and improve the adhesive strength to 1 point.

Electrospark deposition of Fe–Cr–Cu coatings on St3 steel

It is well-known that chromium in metallic compositions forms dense passivating films that slow down corrosion. The new Fe–Cr–Cu coating was applied on St3 steel through electrospark deposition in an anode mixture consisting of copper and titanium granules, with the addition of chromium powder ranging from 4.85 to 13.26 wt. %. The weight gain of the cathode increased nearly twofold with the addition of chromium powder to the anode mixture. The structure of the coatings was analyzed through X-ray phase analysis, scanning electron microscopy, and energy dispersive spectrometry. The phase composition of the coatings consists of ferrochrome and copper. It is demonstrated that the proposed method of electrospark processing allows for the creation of Fe–Cr–Cu coatings with an average chromium concentration ranging from 55 to 83 at. %. The average copper content in the prepared coatings varied from 5 to 16 at. %. The highest concentration of chromium was observed in the coating prepared with the addition of 13.26 wt. % Cr to the anodic mixture. The corrosion behavior of the coatings was investigated using potentiodynamic polarization and impedance spectroscopy in a 3.5 % NaCl solution. Polarization tests have shown that applying Fe–Cr–Cu coatings to St3 steel can increase its corrosion potential by 12 to 19 % and reduce the corrosion current by 1.5 to 3.4 times. The microhardness of the coating surface ranged from 3.08 to 4.37 GPa, and the coefficient of friction ranged from 0.75 to 0.91. The maximum hardness and the lowest coefficient of friction were observed in the coating with the highest chromium content. It has been demonstrated that Fe–Cr–Cu coatings can enhance the wear resistance of the surface of St3 steel by 1.5 to 3.8 times.

Influence of the Surface Quality of Substrates during Electrospark Deposition

The deposition of protective coatings can significantly improve the corrosion resistance and tribotechnical behavior of the surface of metal parts. Surface preparation before a coating deposition increases the cost per unit area of coating. Substrates were prepared from steel St3 with the sur-face roughness Ra from 0.01 to 0.597 µm, as well as with a rust layer, and the electrospark deposition (ESD) of a Cr-Fe-Cu coating was carried out. The conducted studies lead to the conclusion that the initial surface roughness of St3 steel in the Ra range from 0.01 to 0.597 µm does not affect the material deposition nature during ESD and the structure of the deposited coatings. This is unambiguously confirmed by the data on oxidation resistance and tribological behavior of coatings. With this in mind, it can be concluded that the method of ESD with a non-localized electrode with the addition of chromium powder provides high reproducibility of the deposited coatings. ESD can clean the rust layer to some extent, but it is not possible to completely get rid of it, and large pores are present in the formed coating. This was reflected in a significant decrease in the oxidation resistance and the wear resistance of the coatings.

Preparation of a Mixture of Tungsten and Chromium Powders via Magnesium Vapor Reduction of W and Cr Oxide Compounds

Preparation of a Mixture of Tungsten and Chromium Powders via Magnesium Vapor Reduction of W and Cr Oxide Compounds

Comparative Study on the Compression Sintering Performance of Different Kinds of Copper-Chromium Powder Applied to Electrical Contact Materials

In this paper, the pressing and sintering properties of three kinds of copper-coated chromium composite powder and copper-chromium mechanical mixed powder with the same copper content were compared and studied. The copper-coated chromium composite powder was prepared by a diffusion sintering method, a liquid electroless plating method, and a diffusion sintering method with an added binder. The results show that with the increase in copper content, the pressing advantage of copper-clad chromium powder is more obvious. The density, hardness, and size shrinkage of the sintered sample are more stable. Moreover, the uniform distribution of Cu and Cr in the copper-coated chromium powder sintered sample can effectively improve the composition uniformity of Cu Cr electrical contact alloy.

Improvement of optical and conductivity properties of SnS2 via Cr doping for photovoltaic applications

Tin disulfide doped with chromium (Sn1−xCrxS2) powders with different molar ratios (x = 0, 2, 4, 6, and 10 at%) were synthesized using a low-cost hydrothermal technique. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), UV-Vis spectroscopy, and electrochemical impedance spectroscopy (EIS). The Sn1−xCrxS2 samples maintained the hexagonal structure with space group (S.G.) P-3m1 from the SnS2 structure, according to XRD and Raman measurements. Cr doping was confirmed by EDS, where Cr partially substituted Sn in the SnS2 structure. SEM images also displayed good homogeneity and smaller particle sizes as Cr doping increased. HRTEM and selected-area electron diffraction (SAED) analysis showed high crystallinity of the synthesized samples. The optical bandgap energy (Eg) of the Cr-doped samples with x = 6% was found to be the lowest among the measured values, and even lower than that of the pure SnS2 sample. The conductivity of the samples was measured through-plane using EIS, and the Sn1−xCrxS2 samples with x = 6% again showed superior conductivity performance within the investigated temperature ranges. These findings further support the potential of Cr-doped SnS2 systems for use as a buffer layer in photovoltaic applications.

Investigation of Magnesium and Chromium Fillers FSW Dissimilar Joint of AA6063 and AA 5154

Friction stir welding (FSW) is a solid-state metal joining process. There is no melting and recasting of metal while welding is used. Some of the defects commonly encountered in FSW are tunnel defect, bond, cracks, pin holes, and pipping defects. The defects occur because of improper metal mixing and less heat input in the weld nugget zone. In the fusion welding process, a filler rod is employed to form a quality weld with superior mechanical properties. In this work magnesium and chromium powders are used as filler materials. The purpose of this study is to ascertain whether filler materials and manufacturing processes have an impact on the weld nugget zone spot weld joint formation as well as the mechanical and abrasive properties of welded joints. This study's FSW filler materials mixing ratio and process parameters were improved by using the Central Composite Design (CCD) idea, which is discussed in more detail below Response Surface Methodology (RSM). The best empirical relationship between the parameters was provided by the CCD. The mathematical relationships were established to forecast the maximum tensile strength, maximum weld nugget hardness, and minimum corrosion rate by incorporating filler materials with process parameters. The optimal processing factors combination is predicted by conducting the validation test. The optimum parameters were the tool rotatory speed 600–1000 revolution per minute, welding speed 60 to 180 mm/min, plunge depth of 0.05 to 0.25 mm, center distance between the sample is 0–4 mm, as well as powder mixing ratio of 90 : 10, 92.5 : 7.5, 95 : 5, 97.5 : 2.5, and 100 : 0, the tensile test, microhardness, and corrosion rate analysis were conducted on the weld specimen. The welded test specimen provides better joint strength, weld nugget hardness, and enhanced corrosion resistance properties. The microstructure analysis shows the fine grain structure and homogeneous distribution of filler material with the base metal in the welded area.

Formation of functional protective chromium-based coatings by friction cladding

Corrosion damage to metal parts and structures is one of the most important scientific, technical and economic problems. Coatings based on chromium are widely used in modern mechanical engineering. They are used both to solve problems related to the restoration of the size and shape of the surfaces of worn parts, and to improve performance, for example, wear and corrosion resistance, heat resistance, reflective and protective and decorative ability, etc. One of the promising methods for the formation of anti-corrosion coatings is the technology of friction cladding using a flexible tool - a rotating wire metal brush. The article studies coatings formed by friction cladding from donor materials (sintered composites) containing powders of chromium (about 80 %), zinc, copper, tungsten carbide, tungsten-cobalt, hexagonal boron nitride, thermally expanded graphite. The chemical composition of donor materials and the resulting coatings was studied by X-ray diffraction analysis. It was determined that the composition of the obtained coatings based on chromium correlates with the composition of donor materials, however, it additionally contains elements of nickel and iron. It is assumed that iron in the composition of the coating appears as a result of cutting off the particles of the steel base by the bristles of the brush and transferring them to the forming layer of the coating. The nickel content indicates that particles of the wire bristle material of the brush are also introduced into the coating layer. Corrosion tests were carried out in a salt fog chamber KST-2 according to GOST 9.308-85 of samples with coatings obtained by galvanic chromium plating and friction cladding. The coated samples were kept in the chamber for 192 hours. The galvanized coating withstood the test without any signs of corrosion. Traces of corrosion appeared on friction clad coatings, while on all samples the corrosion area was no more than 7 %. It is conditionally accepted that coatings obtained by friction cladding have satisfactory corrosion resistance. The results of X-ray fluorescence analysis of the chemical composition of donor materials and coatings were obtained with the financial support of the Ministry of Science and Higher Education of the Russian Federation (Project No. FZRU-2020-0011). The results of tests for corrosion resistance of samples with applied coatings were obtained with the financial support of the Belarusian Republican Foundation for Basic Research (grant T21ET-005).

Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding with Al-Cr-Ni Unconstrained Metal Powders: Thermodynamic Interpretation of Gas Reactions

Unconstrained metal powders of chromium and nickel, in combination with aluminium, were used in the submerged arc welding (SAW) process to simplify weld metal alloying. Unconstrained metal powders refer to non-alloyed metal powders that are not constrained in tubular wire, such as fluxed-cored and metal-cored wire. Aluminium powder is used to control the oxygen potential at the molten flux–weld pool interface. The results presented here show that the addition of aluminium powder to the weld metal enhances Cr and Ni yields to 89% for Cr and 91% for Ni, compared to lower values reported in pre-alloyed powder application. Alloying of the carbon steel in the base plate and weld wire combination was achieved at 6.0% Cr, 6.2% Ni, and 4.5% Al, with the weld metal oxygen controlled to 162 ppm O. Thermodynamic analysis was applied to investigate the likely gas reactions in the arc cavity emanating from the chemical interaction between Cr, Ni, and Al. The effects of gas-based chemical reactions on the yield of Cr and Ni to the weld pool are discussed and incorporated into our SAW reaction flow diagram. Overall SAW process productivity gains can be accomplished by using unconstrained metal powders to alloy the weld metal because expensive and time consuming steps, such as the manufacturing of alloyed wire and alloyed powder, can now be eliminated.

Parametric optimization of friction stir process for developing high strength and wear-resistant chromium reinforced NiAl bronze composite

The present study focuses on fabricating a chromium-reinforced nickel aluminium bronze (NAB) composite using an optimized multi-pass friction stir processing (FSP) technique. The tool rotation, tool traverse speed, and volumetric concentration of the reinforcement were taken as input process parameters, whereas the ultimate tensile strength (UTS), yield strength (YS), percentage elongation (% E), microhardness, and sliding wear rate were taken as output responses. Taguchi-Grey relational analysis (GRA) was utilized for optimizing the input process parameters, which were 1000 r.p.m., 28 mm min−1 and 15.7%, respectively. The most significant parameter was traverse speed, followed by tool rotation and volumetric concentration of the reinforcement. FE-SEM, EDS, and XRD analyses were performed to characterize the as-cast NAB, chromium powder, and FS-processed composite. The tensile strength and wear resistance of the processed composite are enhanced compared to the base NAB alloy on account of significant grain refinement due to the stirring action of the tool pin in the processed zone and the dispersion of chromium reinforcement. The wear rate of the composite was reduced as the tool rotation, traverse speed, and Cr particle volume concentration were increased. The maximum UTS of the prepared composite was 701 MPa, whereas the UTS of the as-cast NAB was 620 MPa. It was observed that as-cast NAB exhibited a hardness value of 286 HV, which was improved to 385 in the FSPed prepared composite. It was found that as-cast NAB exhibited 7.0 × 10–6 gm m−1 of wear rate, whereas the FSPed composite showed a minimum wear rate of 5.5 × 10–6 gm m−1. The microstructural examination revealed that the wear mechanism in the case of as-cast NAB was primarily adhesion, whereas the abrasion was found to be the governing mechanism of material removal in the processed composite.

Prediction of Filler Added Friction Stir Welding Parameters for Improving Corrosion Resistance of Dissimilar Aluminium Alloys 5052 and 6082 Joints

Abstract The aluminium alloys 5052 and 6082 are extensively used in manufacturing lighter structural members, having improved strength and resistance to corrosion. Magnesium (Mg) and Chromium (Cr) powder were the filler materials selected for enhanced corrosion protection properties in this investigation. Friction stir welding (FSW) process parameters viz., spindle speed, welding speed, shoulder penetration, the centre distance between the holes and filler ratio are used to forecast the minimum corrosion rate from different weld regions of AA5052-AA6082 dissimilar joints. Response surface methodology based on a central composite design was used to evolve the mathematical models and estimate dissimilar FSW joints’ corrosion rates. Response optimization shows that the minimum corrosion rate was achieved by the welding parameters of spindle speed 1000 rev/min, welding speed 125 mm/min, holes spacing of 2 mm and filler ratio 95% of Mg and 5% of Cr.

Growth Mechanism of Chromium Carbide Coating on Porous Carbon Paper

AbstractIn this paper, Cr7C3 coating is prepared on porous carbon paper by the disproportionation reaction of Cr2+ in NaCl–KCl molten salt at 800–900 °C for 40–80 min. Effects of the molar ratio of chromium powders, temperature, and reaction time are investigated. The composition and microstructure of the coating are characterized by X‐ray diffraction and scanning electron microscopy. Finally, the growth mechanism of Cr7C3 coating from the perspective of thermodynamics and kinetics is discussed.

Effect of Silicon on the Surface Modification of Al-Cr Powder Cathodes Subjected to Vacuum Arc Treatment

Al-Cr and Al-Cr-Si composite cathodes were obtained by the hot compaction of aluminum, chromium, and silicon powder mixtures. The phase transformations in the surface layer of the Al-Cr-Si composite cathodes subjected to the arc heating were considered. The elemental and phase compositions of the modified cathodes’ surfaces were studied using X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The effect of the silicon addition on the structural evolution in the cathode surface during arc evaporation is shown. It was found that an arc impact on the cathode surface resulted in the melting and consequent crystallization of the multiphase mixture of intermetallic compounds and eutectic in the cathode surface layer. Cathode surface layers were found to be depleted of aluminum and silicon due to the ejection of these elements in drop form from the Al-Si liquid layer on the cathode surface. This can result in the change in the elements ratio in the deposited coating as compared with that in the cathode and thus influence the coated tools’ durability.