Cathodic Arc Evaporation Research Articles

Oxidation behavior of arc evaporated TiSiN coatings investigated by in-situ synchrotron X-ray diffraction and HR-STEM

Owing to its excellent mechanical and thermal properties and outstanding oxidation resistance, TiSiN is used for protective hard coatings for cutting applications. While several reports confirm the oxidation stability of TiSiN up to temperatures above 800 °C, literature is currently lacking a thorough investigation of the oxidation sequence of this coating system. Thus, in this study the oxidation mechanism of TiSiN was monitored via in-situ synchrotron X-ray diffraction (XRD) and complemented by a detailed analysis of the microstructure and elemental composition of oxidized coatings. A TiSiN coating was deposited by cathodic-arc evaporation in an industrial scale deposition plant. In-situ synchrotron XRD experiments of the powdered coating showed an oxidation stability up to ~830 °C, followed by the formation of both, rutile and anatase TiO2 with increasing temperature. The formation of anatase during oxidation was confirmed by Raman and XRD investigations on a solid coating. High-resolution scanning transmission electron microscopy investigations revealed the oxidation of only several hundred nm of the coating surface after oxidation at 930 °C for 5 min, while increasing the temperature to 1130 °C resulted in full oxidation of the Ti(Si)N nanocrystals, accompanied by high porosity and significant grain coarsening. Furthermore, elemental analysis showed the presence of TiO2 grains surrounded by an amorphous Si-O-N phase as well as the formation of a TiO2 top layer due to diffusion of Ti to the surface. The obtained results provide detailed and novel insight into the oxidation mechanism of TiSiN as well as on the microstructure of oxidized TiSiN coatings.

Achieving machining effectiveness for AISI 1015 structural steel through coated inserts and grey-fuzzy coupled Taguchi optimization approach

Multi-objective optimization technique has become an essential step in the selection of cutting parameters. The intension of this research study is to analyze the performance characteristics of coated carbide inserts on their measured output responses during machining AISI 1015 steel. This paper targets to optimize the machining parameters such as speed, cutting depth, feed rate, cutting fluid flow rate, and coating material when multiple responses like surface roughness and flank wear were considered at the same time during turning. This research study also intends to examine scientifically the effect of machining parameters on quality measures during machining structural AISI 1015 steel. Cathodic arc evaporation–coated titanium aluminum nitride (TiAlN), titanium aluminum nitride/tungsten carbide-carbon (TiAlN/WC-C), and uncoated CNC inserts were used for the study. SEM and energy-dispersive X-ray analysis were performed to confirm the presence of coated elements. Micro-hardness was measured for coated, pure inserts, and TiAlN/WC-C-coated tool exhibited a higher hardness of 22.11 GPa compared with pure and coated tools. Five process parameters were used for this study, each at three stages. The experimental design was laid based on Taguchi’s L27 orthogonal array. In this research study, a multi-objective hybrid optimization technique comprising grey relation and fuzzy logic conjugated with the Taguchi design of experiments was used. The process parameters were optimized by grey relation analysis followed by fuzzification using Mamdani fuzzy engine and then optimized through Taguchi analysis. The parameter combination of speed 500 rpm, depth of cut of 1 mm, a feed rate of 0.05 mm/rev, cutting fluid flow rate at high level, and TiAlN/WC-C coating was found to be the optimum input parameters. The confirmatory test was also performed to validate the hybrid optimization approach.

Effect of nitrogen pressure and substrate bias voltage on the properties of Al–Cr–B–N coatings deposited using cathodic arc evaporation

Cathodic arc evaporation deposition method was applied to forming Al–Cr–B–N coatings. The effect of nitrogen pressure (pN2) and substrate bias voltage (UB) on the properties of the coatings synthesized using Al50Cr30Br20 cathode was investigated. The chemical and phase composition of the coatings, their surface morphology together with the mechanical, tribological and anti-corrosion properties were investigated.X-ray diffraction investigations have revealed the coatings phase composition. It is the mixture of h-AlN and c-CrN phases with crystallite size of about 4 nm. X-ray photoelectron spectroscopy has revealed amorphous BN phase in the investigated coatings. The majority of the coatings exhibit good adhesion, with the critical load above 75 N, except from the coating synthesized at the nitrogen pressure of 2 Pa. Coatings synthesized under various nitrogen pressure have a similar coefficient of friction of about 0.67. The wear resistance for these coatings increases with the nitrogen pressure during their synthesis. Friction coefficient of the coatings increases with substrate bias voltage, while the wear rate decreases.Wear and corrosion tests show that the coating deposited under pN2 = 4 Pa and UB = −100 V is the most resistant to wear and corrosion from the sets of coatings tested.

Effect of Silicon Concentration on the Properties of Al-Cr-Si-N Coatings Deposited Using Cathodic Arc Evaporation.

The current market requirements are related to the introduction of new protective coatings for tools and machine parts with much better performance properties. These requirements are met by the AlCrSiN coatings; however, knowledge on the adhesion of these coatings to the substrate, as well as on their corrosion resistance, is deficient. The article presents the results of technological works on the coating deposition from AlCrSi cathodes with a silicon concentration from 0 at% to 10 at% by the cathodic arc evaporation and the results of systematic studies of their structure, mechanical, tribological and electrochemical properties. A correlation between the above-mentioned properties and the silicon concentration in the AlCrSiN coatings has been found and discussed. The coatings formed from cathodes containing less than 5 at% Si crystallize in the cubic structure. The size of the crystallites decreases with the silicon concentration increase. The coatings are characterized by a high hardness with a maximum of about 37 GPa (2 at% Si). The adhesion of the coatings is almost independent of the concentration of silicon. The wear rate is about one order of magnitude higher for coatings deposited from cathodes with a silicon concentration of 5 at% and 10 at% compared to a coating with a lower silicon concentration. This finding is consistent with the results of corrosion resistance studies. The coating deposited from the cathode with 10 at% of silicon exhibits the best anticorrosion properties against the salt solution.

Insights into the role of the layer architecture of Cr–Ti–N based coatings in long-term high temperature oxidation experiments in steam atmosphere

Knowledge on hard coatings has been applied in the energy field extending their use as protecting coatings of steam power generation plants components. The role of the layer architecture of Cr–Ti–N based coatings deposited by reactive cathodic arc evaporation on P92 steel substrates was studied with the focus on their oxidation resistance at 650 °C in 100% steam atmosphere up to 2000 h. Characterization of the coatings was performed by gravimetry, scanning electron microscopy, electron probe microanalysis, glow discharge optical emission spectroscopy, X-ray diffraction, thermodynamic simulations using the CALPHAD method, Rockwell C indentation and nanoindentation. The layered arrangement improves the oxidation resistance of TiN under the working conditions of steam power plants, as well as the mechanical properties of CrN. The produced architectures performance under the described working conditions boosts the understanding of the processes taking place at high temperature, making possible the design of optimal coatings combining the best behavior of both nitrides for each specific application, reaching a corrosion protection at high temperature in water vapor comparable to that of CrN and a hardness and Young's modulus as high as those of TiN.

Investigation of physical and electrical properties of TiN-coated SS316L as bipolar plate of proton exchange membrane fuel cells

ABSTRACT In this research, TiN films were deposited on the SS316L substrate by cathodic arc evaporation technique, to use as bipolar plates in proton exchange membrane fuel cells. The effect of substrate surface roughness and film thickness on the interfacial contact resistance and corrosion properties of the TiN films was investigated. Characterization of deposited films was performed by XRD, XRF, ICR, contact angle, and FESEM equipped with energy-dispersive spectroscopy. Electrochemical and surface properties of deposited films were studied by potentiodynamic scanning, electrochemical impedance spectroscopy, and AFM analysis. It is observed that the surface roughness of the substrate, before deposition, has a significant impact on the final properties of TiN coating, especially when the coating thickness is less than 1.2 µm. All of the coated samples showed better corrosion resistance in comparison to the substrate, and the corrosion current density decreased from 1.65 to 0.16 μA cm–2 when coating thickness increased from 0.6 to 1.5 µm.

The effect of carbon doping on microstructure, mechanical properties, wear resistance and cutting performance of AlTiCN coating

A series of AlTiCN coatings with different carbon contents (0–0.7 at.%) were deposited on YG10 (WC + 10 wt.% Co) cemented carbide by cathodic arc-evaporation of Ti-Al/Ti-Al-C targets in a mixture of Ar and N2 gases. The influence of carbon doping on microstructure, mechanical properties, wear resistance and cutting performance was systematically investigated by comparing carbon-free coating and coatings with different carbon contents. The microstructure of the coatings has been changed significantly with the addition of C, and the amorphous domains appear when the doping amount of C is among 0.2–0.5 at.%. Instead of forming bonds with other elements in the coating, carbon only acts as a growth inhibitor. When the carbon content is 0.2 at.%, the hardness of the coating significantly decreased, but changes a little with the carbon content continue to rise. The addition of C significantly improves the wear resistance of the coating, which is mainly attributed to the transformation of the crystalline state and the formation of the dense Al2O3 oxide layer. Among them, the coating with a carbon content of 0.2 at.% has both excellent wear resistance and cutting performance.

Controllable preparation of micro-textures on WC/Co substrate surface by an integrated laser-dry etching process for improving PVD coatings adhesion

The micro-texture fabricated on the substrate surface of coatings is an established method for enhancing the Physical Vapor Deposition (PVD) coatings adhesion. Currently, laser micromachining is widely used to prepare the micro/nano-texture. Nevertheless, it has a problem of low processing accuracy, such as irregular texture edges and irregular protrusions inside the textures. Here, we propose an ion beam etching (IBE)-assisted laser machining approach to fabricate micro-texture, and the effect of IBE/laser textures on the PVD coatings adhesion is revealed for the first time. The profile evolution mechanism of the micro-textures on the cemented carbide during etching process was investigated. By IBE-assisted laser machining, a ring-shaped microholes array with high precision and controllability was fabricated on the cemented carbide substrate surface. Then, the textured substrates were coated with TiAlN materials using cathode arc-evaporation technique. The scratch tests and dry wear tests on the coatings with the textured substrates were carried out, demonstrating that the IBE/laser textured coatings exhibited higher adhesive strength compared to that of the untextured and laser textured ones. Thus, the IBE-assisted laser machining shows a great potential in the preparation of high precision micro-textures for enhancing PVD coatings adhesion.

The Effect of the Metal Phase on the Compressive and Tensile Stresses Reduction in the Superhard Nitride Coatings

The influence of the compressive and tensile stresses forming in the nanostructured Ti–Al–N coatings during deposition on their physical-mechanical properties was studied. The modifying influence of metal components (Ni and Cu) introduction into Ti–Al–N coatings, which do not interact with nitrogen and have limited solubility with the nitride phase, was also under research. Coatings were deposited on WC–(6 wt.%)Co carbide cutting inserts with an arc-PVD method using a cathodic vacuum arc evaporation apparatus. The introduction of Ni and Cu to the composition leads to the reduction of nitride phases grain size in both investigated coatings from 120 to 10–12 nm for Ti–Al–Cu–N and to 15–18 nm for Ti–Al–Ni–N. Thus, the hardness increases from 29 to 43 and 51 GPa for the mentioned above coatings, respectively. Meanwhile, Ti–Al–Cu–N and Ti–Al–Ni–N coatings are characterized by tensile stresses about 0.12–0.32 MPa against the much higher value of compressive stresses in Ti–Al–N coatings (4.29–5.31 GPa). The modification of Ti–Al–N coatings also leads to the changing of their destruction mechanism during the scratch-test. The critical loads characterizing the emergence of the first cracks in the coatings and complete abrasion of the coating (Lc1 and Lc3) were determined. They had the value of 20; 22 N (Lc1) and 64; 57 N (Lc3) for Ti–Al–Ni–N; Ti–Al–Cu–N coatings, respectively. The Lc1 parameter for Ti–Al–N coatings was much lower and was equal to 11 N. Along with those, Ti–Al–N coatings destructed according to the adhesion mechanism when the critical load was 35 N. In addition, the decreasing level of compressive stresses in Ti–Al–Cu–N and Ti–Al–Ni–N coatings as compared to that in the Ti–Al–N coating, their crack resistance during multi-cycle shock-dynamic impact test was significantly higher. The results can indicate that high hardness and crack resistance of the coatings is to a greater extent determined by coatings nanostructuring, not the stresses value. In addition, it confirms the possibility to obtain coatings with low stresses value while maintaining their superhardness.

Structure and Properties of AlCrN Coatings Deposited Using Cathodic Arc Evaporation

Al–Cr–N coatings were formed at various nitrogen pressures, substrate bias voltages and substrate temperatures using cathodic arc evaporation. The relationship between technological parameters and properties of the coatings was investigated. The phase and chemical composition of the coatings, roughness, hardness, adhesion and thermal stability were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), micro-indenter, Rockwell, scratch tester and thermomechanical methods. The corrosion resistance of selected coatings was also investigated. XRD analysis indicates that the coatings crystallize in a cubic structure and show preferential orientation (200) CrN. With the increase of nitrogen pressure, the preferential orientation changes to (111). EDX analysis shows that as nitrogen pressure increases, the Al/(Al + Cr) rate decreases. Microscopic observations indicate that the number of macroparticles reduces as nitrogen pressure increases. As a result, the surface roughness parameter Ra of the coatings decreases. The effects of deposition temperature, nitrogen pressure and substrate bias voltage on the mechanical and tribological properties of the coatings were investigated. It was found that the above parameters influence the mechanical properties in different ways. The hardness and adhesion of coatings formed at higher temperatures was lower. Coatings formed under a higher nitrogen pressure or substrate bias voltage were characterized by higher hardness and better wear resistance.

An investigation on microstructure and milling performance of arc-evaporated TiSin/AlTiN film

In this work, TiSiN/AlTiN multilayer film was deposited on cemented-carbide solid end mill tools by cathodic arc evaporation. The multilayer consisted of CrN buffer layer, Al0.67Ti0.33N adhesion layer, Ti0.9Si0.1N/Al0.67Ti0.33N alternate layer, and Ti0.9Si0.1N outlayer. An investigation on microstructure, mechanical properties, high-temperature wear rate, and milling performance of TiSiN/AlTiN multilayer film was conducted. The results indicate that the as-deposited TiSiN/AlTiN film exhibits a mixture phase of fcc-TiN and fcc-(Ti, Al)N. The hardness and elastic modulus of the TiSiN/AlTiN film are 41.7 ± 1.6 GPa and 340 ± 17 GPa, respectively. The wear rate of TiSiN/AlTiN film changes slightly when the experiment temperature is below 400°C, and then increases with the temperature increases to 600°C. Indentation hardness of TiSiN/AlTiN changes can be maintained above 40 GPa upon annealing to 800°C. However, the hardness of the film decreases from above 40 GPa to ⁓30.6 GPa when the annealing temperature increases to 1000°C. During dry milling, the TiSiN/AlTiN film reduces the adhesion between the coated tool and machined material SKD 11, leading to a low cutting force and cutting temperature.

In Vitro Corrosion and Tribocorrosion Performance of Biocompatible Carbide Coatings

The present study aims to explain the corrosion and the tribocorrosion performance in simulated conditions of the human body by the level of stress, adhesion of coating to substrate, roughness, and hardness. The coatings were synthesized by the cathodic arc evaporation method on 316L stainless steel substrates to be used for load bearing implants. Structure, elemental, and phase compositions were studied by means of energy dispersive spectrometry and X-ray diffraction, respectively. The grain size and strain of the coatings were determined by the Williamson–Hall plot method. Tests on hardness, adhesion, roughness, and electrochemical behavior in 0.9% NaCl solution at 37 ± 0.5 °C were carried out. Tribocorrosion performances, evaluated by measuring the friction coefficient and wear rate, were conducted in 0.9% NaCl solution using the pin on disc method at 37 ± 0.5 °C. TiC and ZrC exhibited a (111) preferred orientation, while TiNbC had a (200) orientation and the smallest crystallite size (8.1 nm). TiC was rougher than ZrC and TiNbC; the lowest roughness was found for TiNbC coatings. The highest hardness and adhesion values were found for TiNbC, followed by TiC and the ZrC. All coatings improved the corrosion resistance of 316L steels, but TiNbC showed the best corrosion behavior. TiNbC had the lowest friction coefficient (1.6) and wear rate (0.99 × 10−5 mm3·N−1∙m−1) values, indicating the best tribocorrosive performance in 0.9% NaCl at 37 ± 0.5 °C.

Effects of (Cr,Al)N and (Cr,Al,Mo)N coatings on friction under minimum quantity lubrication

In today's mobility applications, efficiency is a key requirement. While in conventional mobility, increased efficiency contributes to reduce greenhouse gas emissions, in e-mobility every increase in efficiency translates also directly into increased battery range, which in turn contributes to reduced CO2 emission. Therefore, different approaches like the reduction of lubricant viscosities and the reduction of lubricant quantities towards minimum quantity lubrication are pursued. A promising approach to meet the increasing demands are (Cr,Al)N and triboactive (Cr,Al,Mo)N coatings.Within this work (Cr,Al)N and triboactive (Cr,Al,Mo)N coatings were investigated at a twin-disk test rig in highly-loaded rolling-sliding contacts. The coatings were deposited by means of cathodic arc evaporation (CAE) on the case hardened steel (AISI 5115) and tribologically investigated under minimum quantity (MQL) lubrication with a low viscosity, sulphur and phosphorous doped, polyalphaolefine oil. Compared to the uncoated steel, the coatings lead to a higher system stability, which can be characterized by a stable friction behavior, and wear reduction. Tribochemical interactions between coatings and lubricant were analyzed by means of Raman spectroscopy and reveal the in situ formation of MoS2. Furthermore, the coatings exhibit lower thermal conductivities compared to the uncoated steel, which might also affect friction reduction. The results show the high potential of (Cr,Al)N and triboactive (Cr,Al,Mo)N coatings under high tribological load.

Multi-Functional Cr-Al-Ti-Si-N Nanocomposite Films Deposited on WC-Co Substrate for Cutting Tools.

Multi-functional quinary Cr-Al-Ti-Si-N thin films were deposited onto WC-Co substrates using a cathodic arc evaporation system. In this study, the influence of silicon contents on the microstructure, mechanical, tribological, and oxidation properties of Cr-Al-Ti-Si-N thin films were systematically investigated and correlated for application of cutting tools. Based on results from various analyses, the Cr-Al-Ti-Si-N films showed excellent properties including mechanical, tribological, oxidation and adhesion values compared with those of the Cr-Al-Ti-N film. The Cr-Al-Ti-Si-N films with a Si content of around 4.21 at.% exhibited the highest hardness of 45 GPa, very low friction coefficient of 0.38 at room temperature against an Inconel alloy ball and superior adhesion property (105 N). The Cr-Al-Ti-Si-N films also showed excellent oxidation resistance after annealing in the ambient air at 1000 °C. Therefore, the Cr-Al-Ti-Si(4.21 at.%)-N films could be help to improve the performance of machining and cutting tools with application of the films.

Effect of lanthanum addition on the structure evolution and mechanical properties of the nanocomposite Ti-Si-N coatings

The novel nanocomposite Ti-Si-La-N coatings were deposited using the cathodic arc evaporation process. The effect of different lanthanum contents (0–13 at.%) on the chemical composition, structural evolution, and mechanical properties of nanocomposites was studied. Analysis of structure showed that all Ti-Si-La-N series consisted of a crystalline face-centered cubic (fcc) TiN. Coatings were characterized by the (2 0 0)texture, which intensity vastly dropped at La > 6.6 at.% along with the formation of the La-based amorphous phase. The increase in lanthanum content led to a significant decrease in the crystallite size from 6.9 nm to 1.7 nm, and slight enlargement of the lattice parameter from 4.244 Å to 4.285 Å. The highest values of hardness (38.7 ± 1 GPa), wear resistance (H/E = 0.095), and resistance to plastic deformation (H3/E2 = 0.350 GPa) were observed for the coatings with 0.4at.% of lanthanum. In contrast, higher La concentrations caused deterioration of the coating properties.

The effect of duty cycle on the mechanical and electrochemical corrosion properties of multilayer CrN/CrAlN coatings produced by cathodic arc evaporation

ABSTRACT Multilayer CrN/CrAlN coatings were deposited on the 420-SS by the cathodic arc evaporation system with different duty cycles of bias-voltage. The deposited films were characterized by XRD and FESEM techniques. Mechanical, electrochemical, and surface properties of deposited films were studied by nano-indentation, electrochemical, and AFM analysis. Microstructure investigation confirmed the formation of adhesive and dense nanostructure multilayer film. Increasing the duty cycle led to the decrease in the coating grain size and promoted the hardness to 34.1 ± 4 GPa. A clear reduction of size and distribution of macroparticles was observed by using large repulsive force at a high duty cycle. By increasing the duty cycle, the coating deposition rate was increased from 1.23 to 1.38 µm/h and the surface roughness was decreased from 155 to 70 nm. The lower corrosion current density was obtained for the film applied at the 40% duty cycle (0.59 µA cm−2), which was about 10-order of magnitude less than the substrate.

Anti-wear Cr-V-N coating via V solid solution: Microstructure, mechanical and tribological properties

V-containing solid solution was considered as a promising way to improve the mechanical and tribological properties of hard coatings due to the mechanism of solid solution as well as the induced V-based Magnéli lubricant during friction process. In this work, Cr-V-N coatings with different V contents were prepared on polished cemented carbide and P-type Si (100) wafers by cathodic arc evaporation. The microstructure, mechanical and tribological properties of the coatings with varied V content were discussed. When the content ranged from 0.32 to 31.14 at.%, V entered into the lattice of CrN crystal in the form of solid solution without affecting the coating's phase composition. CrN phase with (111) orientation was formed for all Cr-V-N coatings, and the coating with 31.14 at.% V content showed the weakest crystallinity. The introduction of V still retained the composited coatings with high toughness and excellent adhesion strength of around 100 N on cemented carbide substrates. The maximum elastic modulus and hardness reached up to 438.5 ± 5.3 GPa and 20.0 ± 1.0 GPa, respectively, with V content at 16.55 at.%. Tribological tests at room temperature demonstrated that the friction coefficient of Cr-V-N coatings was relatively low, which was between 0.26 and 0.36. The wear rate was in the order of magnitude of 10−7 mm3N−1 m−1, and the lowest wear rate was 2.5 × 10−7 mm3N−1 m−1 with V content at 0.32 at.%. The friction coefficient and wear rate both increased with the increase of V content. The wear rate of the coatings with high V content (31.14 at.%) was almost four times higher than that of low V content (0.32 at.%) coatings.

Observation of Coating-Substrate Adhesion of Nanocomposite Hard Coating with Respect to the Deposition Parameters and Surface Finishing of Cemented Carbide Substrate

The paper deals with the issue of coating and surface finishing with edge preparation prior to the coating. Nanocomposite AlCrSiN hard coatings were deposited on WC-Co substrates with a negative substrate bias voltage in range of-80 to-120 V using cathodic arc evaporation system. The effect of variation in the bias voltage on the coating-substrate adhesion and nanohardness was investigated. The maximum nanohardness of coating was 37.7 ± 1.5 GPa with the good coating-substrate adhesion. Static Mercedes indentation test was performed on a Rockwell-type hardness tester. The indents were studied by scanning electron microscope to evaluate the coating-substrate adhesion. The H to E ratio that represents resistance to the plastic deformation was determined. The influence of surface roughness and time of used surface finishing methods on the coating-substrate adhesion was also investigated.

Tribological Characteristics and Corrosion Resistance of Coatings Obtained by Electrospark Alloying, Pulsed Cathodic Arc Evaporation, and Hybrid Technology Using TiCNiCr and TiCNiCr–Dy2O3 Electrodes

Single- and double-layer coatings on 40Cr steel substrates have been obtained by electrospark alloying (ESA) and a combination of ESA technology and pulsed cathodic arc evaporation (PCAE) using TiCNiCr and TiCNiCr–Dy2O3 electrodes. The electrodes are obtained by powder metallurgy. The structure and elemental and phase composition of the electrodes and coatings are studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray phase analysis. The tribological properties of the coatings are determined as a result of tests according to the pin-on-disk scheme in contact with the Al2O3 counterbody at loads of 1, 5, and 10 N. The temperature during the tests is T = 20°C. The potential and current density of corrosion are determined using a three-electrode cell with a VoltaLab 50 potentiostat. The results show that the electrodes consist of TiC grains of 12 μm; a solid solution of Ni in Cr; and, in the case of a doped electrode, Dy2O3 up to 5 μm in size. ESA coatings have a low-defect fine-grained structure consisting of regions of a solid solution of Ni and Cr in Fe and titanium carbide grains with a maximum size of 0.3 μm. Coatings with the addition of Dy2O3 have a lower coefficient of friction at loads of 1, 5, and 10 N. All coatings in 1 N H2SO4 are in a stable passive state and have high corrosion resistance: the corrosion current density of the coatings is at least 4 times lower than the values obtained for a 40Cr steel substrate.

Tribological characteristics and corrosion resistance of coatings obtained by electrospark alloying, pulsed cathodic arc evaporation and hybrid technology using TiCNiCr and TiCNiCr—Dy2O3 electrodes

Single- and two-layer coatings were deposited on 5140 steel substrates by electrospark alloying (ESA) and a combination of ESA technology and pulsed cathodic arc evaporation (PCAE) using TiCNiCr and TiCNiCr Dy 2 O 3 , electrodes obtained by powder metallurgy. The structure, elemental and phase composition of electrodes and coatings were studied using scanning electron microscopy, energy dispersive spectroscopy, and X -ray phase analysis. Tribological properties of coatings were determined as a result of tests according to the «pin-on-disk» scheme in contact with the Al 2 O 3 counterbody at loads of 1, 5, and 10 N. The temperature during the tests was 20 °C. The potential and density of corrosion current were determined using a three-electrode cell with a VoltaLab 50 potentiostat. The results showed that electrodes consist of 12 pm TiC grains, a solid solution of Ni in Cr, and Dy 2 O 3 up to 5 μm in size in case of a doped electrode. ESA coatings had a low-defect fine-grained structure consisting of regions of a solid solution of Ni and Cr in Fe and TiC grains with a maximum size of 0.3 μm. Coatings with the addition of Dy 2 O 3 had a lower friction coefficient at loads of 1, 5, and 10 N. All coatings during the tests in the H 2 SO 4 1N solution were in a stable passive state and featured high corrosion resistance: corrosion current density of the coatings was at least 4 times lower than the values obtained for the 5140 steel substrate.