Tribological Properties Of Coatings Research Articles

Assessment of Wear Resistance of Galvanic Coatings of Restored Parts

The article deals with the analysis of the wear resistance characteristics of composite galvanic coatings using molybdenum disulfide as a solid lubricant on restored parts of the transport vehicles and tractors on a friction path of 500 m. The experiments demonstrated that the wear products of the sample adhere to the counterbody; the size of the wear track of the sample ranges from 328.4 to 386.5 μm; the depth of the wear groove on the surface of the sample is up to 5 µm; friction coefficient of the sample surface – 0.243-1.002; the wear factor of a counterbody made of Stainless Steel AISI 420 having the value of microhardness of 8 GPa and the coating of microhardness of 4.518 GPa is 0.019 and 1.676, respectively. The conducted studies showed that the developed technology for restoring and strengthening worn parts makes it possible to ensure the necessary tribological properties of coatings and a long service life of the restored parts.

Role of the codeposited C and W element on the tribological performance of WS2 coating

WS2 is a widely used solid lubricating material that exhibits applications in various fields, including automotive components, precision instruments, and key parts that require antiwear properties. However, WS2 is highly susceptible to humidity, which significantly limits its practical utility. In order to investigate and enhance the tribological and mechanical properties of WS2 coatings, a method involving codeposition of carbon (C) and tungsten (W) with WS2 was employed using magnetron sputtering, resulting in the successful preparation of W-diamondlike carbon (DLC)/WS2 composite coatings. Subsequent investigations revealed a synergistic effect of C and W through various methods. The addition of W noticeably improved both the nanohardness and Young’s modulus of the W-DLC coatings, thereby further enhancing the mechanical properties of the W-DLC/WS2 composite coatings and improving their wear resistance. However, it was observed that excessive W tended to oxidize, intensifying the abrasive wear of the composite coatings during friction. Moreover, Raman spectroscopy analysis indicated the presence of carbon in the composite coatings in the form of DLC, which served as a lubrication phase. The presence of DLC facilitated the formation of transfer films composed of graphite. Additionally, it was discovered that the number of graphite layers in the transfer films had an impact on the tribological properties of the coatings.

Influence of deposition voltage on tribological properties of W-WS2 coatings deposited by electrospark deposition

Electrospark deposition coatings were prepared with different deposition voltage on CrNi3MoVA steel substrates by using a W-WS2 sintered electrode and their tribological properties were investigated. The microhardness, roughness and tribological properties of the coatings were tested by using Vickers hardness tester, confocal laser scanning microscope and tribometer, and the morphologies, composition and phase structure were obtained by utilizing scanning electron microscopy (SEM), energy dispersive X-ray spectrum (EDS) and X-ray diffraction(XRD). The results showed that with the increase of deposition voltage, the hardness and roughness of the coatings increase. The coatings remarkably increase the tribological properties of CrNi3MoVA steel, and among the three coatings deposited at 40 V, 60 V and 80 V, the coating deposited at 60 V has the smallest friction coefficient and the best wear resistance.

Tribological properties of laser-cladded Fe-based amorphous composite coatings under dry and lubricated sliding

Fe-based amorphous composite coatings are promising surface coating materials, because of their low cost, high hardness, and superior wear resistance. In the present study, Fe-based composite coatings with various amorphous contents (35.9–59.3%) were deposited onto 1045 steel via laser cladding, and the influence of laser-cladding parameters on the amorphous content was analysed. The cross sections of the coating layer and ground coating surface were then characterised in terms of the microstructure, phase composition, amorphous content, grain size, and microhardness. Importantly, the tribological properties of coatings with various amorphous contents under both dry and lubricated sliding conditions with light and heavy loads were systematically investigated. The microstructure of the crystalline/amorphous mixture was found to be a function of the temperature gradient, cooling rate, and chemical composition. The high microhardness was related to the amorphous content and grain size. The tribological properties were found to be insensitive to the amorphous content under both dry and lubricated conditions under light and heavy loads. The manifold morphologies of the wear tracks and the transition of the wear mechanism were the result of the combined effects of the amorphous content, phase composition, and size and distribution of the crystalline phase.

Study on the preparation of CeO2-doped AlCoCrFeNiTi high entropy alloy bioinert coatings by laser cladding: The effect of CeO2 particle size on the tribological properties of the coatings

The AlCoCrFeNiTi high entropy alloy (HEA) bioinert wear-resistant coatings reinforced by doping CeO2 particles were prepared on the surface of Ti6Al4V via laser cladding technique. In order to find out the effect of CeO2 particle size on the tribological properties of AlCoCrFeNiTi HEA coatings, the coatings doped with 1 wt% nano, submicron, and micron CeO2 particles were prepared respectively. The phase composition and microstructure of the coatings were analyzed, and the fracture toughness values of the coatings were tested. Friction and wear properties of the coatings sliding against Si3N4 ceramic grinding balls were tested under dry friction and wet friction (simulated body fluid, SBF) conditions, respectively. The results showed that the CeO2 particle size had a significant impact on the wear mechanisms of the coating and thereby improved its tribological properties. Doping with submicron CeO2 particles had the most significant improvement on the tribological properties of the coatings, followed by micron CeO2 particles, and doping with nano CeO2 particles had the weakest improvement on the tribological properties of the coatings. The distribution of submicron CeO2 particles in the coating was more dispersed and uniform, which significantly reduced the crack sensitivity of the coatings, inhibited the peeling off of the oxide film on the coating surfaces, and played a lubricating role. Under dry friction and SBF conditions, the friction coefficient of the coatings doped with submicron CeO2 particles decreased by 41.81% and 27.27%, respectively, and the wear resistance increased by 55.14% and 50.69%, respectively. This study has important reference value for the development of new bioinert wear-resistant coatings.

Structure, mechanical and tribological properties of Ti-doped and Cr-doped a-C:H:SiOx coatings

The work is devoted to the deposition of Ti- and Cr-doped a-C:H:SiOx coatings on WC-8Co substrates using plasma-assisted chemical vapor deposition and magnetron sputtering methods. The structure, surface morphology, mechanical and tribological properties of coatings are investigated depending on the Ti or Cr content. It is shown that only a small concentration of Ti or Cr in coatings improves their mechanical and tribological properties compared to undoped coatings. The addition of 0.8 at.% Ti to the a-C:H:SiOx coating reduces its wear rate by 3 times, and the addition of 3 at.% Cr to the a-C:H:SiOx coating reduces its friction coefficient by 30% and the wear rate by 10 times. According to VDI 3198 standard, the Ti- and Cr-doped a-C:H:SiOx coatings with a low concentration of metals have the adhesive strength quality HF1. At higher metal concentrations, the properties of the coatings deteriorate due to graphitization of the carbon structure.

Effect of silicon carbide incorporation and heat treatment on tribological properties of electroless Ni–B–W alloy coating

Concentration of reinforcing agents govern various characteristics of electroless composite coatings. In this study, silicon carbide (SiC) particles are incorporated into matrices of electroless ternary Ni–B–W alloy coatings. Addition of variable amounts of SiC into electroless bath solution used for the deposition helped in the fabrication of Ni–B–W-based electroless composite coatings of different compositions. Higher hardness value is noticed in composite coatings fabricated with the 1 g/l concentration of SiC particles in the plating bath. The resultant Ni–B–W–SiC composite coating is then subjected to heat treatment at three different temperatures (250 °C, 450 °C, and 650 °C) to study its effects on microstructural, mechanical and tribological characteristics. Alongside the composite coating, characteristics of Ni–B–W alloy coating are also observed in the same route for comparison. Matrices of as-deposited coatings show short-range order characteristics. Heat treatment at different temperatures affects magnitude of crystallization, degree of dispersion, sizes of precipitates within coatings' matrices differently. Development of various borides, such as Ni3B and Ni2B and several silicides, namely Ni3Si, Ni5Si2, and NiSi within coatings' matrices as a function of heating temperature governs the mechanical and tribological properties of coatings. Cumulative effects of composite coatings fabricated with the 1 g/l concentration of SiC particles in plating solution and heat treated at 450 °C evolved superiority in terms of mechanical and tribological properties as compared to other coated specimens in this study. Heat treatment at a higher temperature (650 °C) causes degradation in coatings’ properties due to the coarsening and coalescence of nickel boride precipitates and grain growth. Moreover, at this temperature, nickel reacts with the SiC particles and produces several nickel silicide phases, namely Ni3Si, Ni5Si2, and NiSi, negatively affecting properties of the composite coatings.

TaC-based wear-resistant coatings obtained by magnetron sputtering and electro-spark deposition for wedge gate valve protection

Ta–Zr–Si–B–C coatings were deposited by magnetron sputtering (MS) of a TaSi2–Ta3B4–(Ta, Zr)B2 multi-component target in an Ar + C2H4 gas mixture. TaC–Cr–Mo–Ni based coatings were obtained by electro-spark deposition (ESD) using TaC–Cr–Mo–Ni electrode. The composition and structure of the coatings were studied using scanning electron microscopy, energy-dispersive spectroscopy, glow discharge optical emission spectroscopy and X-ray diffraction. Mechanical and tribological properties of coatings were determined using nanoindentation and pin-on-disk tests. The study showed that the coatings have a homogeneous and defect-free structure, with the main structural component being the fcc-TaC phase. The MS coating exhibited a 30 % higher concentration of the TaC phase compared to the ESD coating. The TaC crystallite sizes for the MS and ESD coatings were 3 and 30 nm, respectively. The presence of a high fraction of the carbide phase and small crystallite size for the MS coating resulted in superior hardness (H = 28 GPa) compared to the ESD sample (H = 10 GPa). Both coatings exhibited similar values of the friction coefficient (about 0.15) and demonstrated reduced wear rates (<10–7 mm3/(N·m)). The deposition of coatings on a steel substrate led to a decrease in the friction coefficient by five times and the wear rate by four orders of magnitude. Pilot tests were conducted on coatings applied to wedge gate valve of shut-off devices used in the oil and gas industry for pumping liquids. The results indicated that the service life of the steel wedge gate valve increased by 25 and 70 % with deposited MS and ESD coatings, respectively.

Effects of C content on the microstructure, mechanical and tribological properties of TiAlSiCN coatings

The effects of C doping content on the microstructure, mechanical and tribological properties of TiAlSiCN coatings prepared by ion plating are systematically investigated. The results show that the grain is refined with the C content increases to 17.22 at.%, and the (111) and (200) planes present competitive growth, the high C content promotes the preferred orientation of the (200) planes. The hardness of the coating shows a tendency to increase first and then decrease, the coating with C content of 8.15 at.% achieve the highest hardness, while the elastic strain resistance H/E value decreases monotonically. Moreover, it is found that the amorphous carbon (a-C) structure is precipitated with C content above 12.51 at.%. The wear mechanism of the coating against the Si3N4 counterpart is adhesive, and the coefficient of friction (COF) of the coating decreases from 0.4 to 0.2. Thereinto, the reduction in COF is related to the Hertzian contact area as C content below 8.15 at.%. The COF further reduction is attributed to the generation of graphite lubricated structure. However, the wear rate shows first decrease and then increase. Therefore, the preferential C doping content can improve the mechanical and tribological properties of the coatings.

Investigation on microstructure and tribological performances of electrodeposited Ni-W-Y2O3 composite coatings

Nickel-tungsten-yttrium oxide (Ni-W-Y2O3) composite coatings were co-electrodeposited onto low-carbon steel surfaces using the direct current electrodeposition method with a constant current density of 2 A/dm2. The influence of Y2O3 nanoparticles on the microstructure, morphology, microhardness and tribological performance of the composite coatings was investigated. The incorporation of Y2O3 nanoparticles was found to significantly refine the crystallite size of the coatings. The microhardness improvement and superior tribological properties of the Ni-W-Y2O3 composite coatings were attributed to the dispersion strengthening and refine crystalline strengthening effects induced by the addition of Y2O3 nanoparticles. It was also observed that the coating prepared from an electrolyte containing 10 g/L Y2O3 nanoparticles exhibits the highest wear resistance. These results highlight the potential of Y2O3 nanoparticles as a promising additive for enhancing the mechanical and tribological properties of coatings.

Effect of substrate bias on structure and properties of (AlTiCrZrNb)N high-entropy alloy nitride coatings through arc ion plating

This study mainly focused on the effects of different substrate bias on the microstructure, elemental composition, mechanical and tribological properties of (AlTiCrZrNb)N coatings. (AlTiCrZrNb)N high-entropy nitride coatings with different substrate bias parameters were deposited on cemented carbide and silicon wafers using arc ion plating. The results showed that the bias voltage created a high-energy particle bombardment effect to reduce the number and volume of macroparticles brought by arc ion deposition technology; this optimized the surface quality of the coating. (AlTiCrZrNb)N coatings at different bias voltages exhibited a single-sided cubic solid solution structure. Substrate bias can significantly change the preferred orientation of coatings. As bias voltage increased from 0 V to −100 V, the preferred orientation of coatings changed from (111) to (200), and when negative voltage further increased to 200 V, the preferred orientation changed from (200) to (111). Appropriate substrate bias parameters can improve the residual stress, mechanical properties, and tribological properties of coatings. The highest hardness of the coating reached 34.85 ± 2.05 GPa. The lowest average friction coefficient was 0.26, and the lowest wear rate was 8.86 ± 1.05 × 10−6 mm3 ∙ N−1 ∙ m−1.

The effect of WC-CoCr content on hardness and tribological properties of NiCrBSi coatings fabricated by the HVOF process

Although Ni-based alloy composites are commonly used as coatings for the enhancement of tribological properties of structural materials. The achievement of a dense and well-distributed microstructure with high content of reinforcing materials is still a challenge. Herein, we aimed to prepare NiCrBSi/WC-CoCr composite materials with different amounts of WC-CoCr (0–45 wt%) using V-mixer and high-velocity oxy-fuel (HVOF) coatings techniques and evaluated the hardness and tribological properties of the coatings at 500 °C. Particularly, we optimized the distribution of WC-CoCr in NiCrBSi matrix using a set of optimized parameters for mixing and coating processes. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterize the microstructures of the coatings. It was observed that an appropriate balance of hard phase (WC-CoCr splats: 30 wt%) and soft phases (Ni-base alloy: 70 wt%) can lead to a uniform, dense, and well-bonded microstructure resulting in the achievement of high hardness, low wear rate, and friction coefficient. Higher contents of WC-CoCr splat (45 wt%) led to a loosening of the interphase bonding on one hand (due to weak wetting between WC-CoCr splats and uncomplete melting of WC-CoCr splats during coating process), and enhanced oxide formation in the coating owing to alumina insertion (from wearing of alumina balls) on the other hand. Overall, the comparison of the harnesses and friction coefficients obtained in the present work shows how an optimized process could lead to the accomplishment of properties superior to those reported in the works.

Micro-Arcs Oxidation Layer Formation on Aluminium and Coatings Tribological Properties—A Review

This review proposes to carry out a state-of-the-art associated with micro-arc oxidation. Firstly, the different aspects of the growth mechanisms of the oxides are detailed. Then, the formation of micro-arcs and the case of soft-spark treatment are discussed. Then, the electrolytic reactions involved in the layer construction are outlined. We focused on the influence of aluminium alloys on the appearance of the coating and its characteristics before considering the electrolyte formulation. We have concentrated some of our efforts on silicate-based electrolytes, mainly used in research and industry. The importance of electrical parameters in layer formation is detailed later. The main factors studied in the literature are the current source, current density, treatment frequency and duration, and duty cycle. We have also noted the different phase compositions identified in the literature. Finally, since the process is particularly advantageous for protecting the surfaces of aluminium parts against wear, we conclude this review by presenting work on the tribological properties of this coating. In this final section, we highlight the work on the wear-reducing properties and tribological mechanisms identified in the literature. Particular attention is paid to the relationship between the nature of the substrates used, the role of the electrolyte and the counterpart choice on the friction and wear results.

Advanced progress on the significant influences of multi-dimensional nanofillers on the tribological performance of coatings.

Over the past two decades, nanofillers have attracted significant interest due to their proven chemical, mechanical, and tribological performances. However, despite the significant progress realized in the application of nanofiller-reinforced coatings in various prominent fields, such as aerospace, automobiles and biomedicine, the fundamental effects of nanofillers on the tribological properties of coatings and their underlying mechanisms have rarely been explored by subdividing them into different sizes ranging from zero-dimensional (0D) to three-dimensional (3D) architectures. Herein, we present a systematic review of the latest advances on multi-dimensional nanofillers for enhancing the friction reduction and wear resistance of metal/ceramic/polymer matrix composite coatings. Finally, we conclude with an outlook for future investigations on multi-dimensional nanofillers in tribology, providing possible solutions for the key challenges in their commercial applications.

Nanostructural glasscomposite self-lubricant coatings

The results of the study of glass-composite nanostructured self-lubricating coatings are presented. The structural components of these coatings significantly affect the graphitization process and provide an antifriction surface layer of α-graphite. The formation of this layer makes it possible to significantly minimize the contact parameters in the friction region.
 A significant effect of aluminoborosilicate in the form of a glass phase on the tribological properties of coatings is noted. An increase in adhesive strength is achieved by forming a surface layer of glassy sodium silicate. The presence of near-surface particles in the graphite layer does not affect the tribotechnical characteristics of the coatings. The developed glass-composite nanostructured self-lubricating coatings have high antifriction characteristics throughout the entire load-speed range

EFFECT OF ARC CURRENT ON MECHANICAL PROPERTIES OF AlCrN COATINGS DEPOSITED USING CATHODIC ARC EVAPORATION

The AlCrN coatings were formed using cathodic arc evaporation at constant nitrogen pressure and arc current ranged from 50 to 120 A. Scanning electron microscopy, energy dispersive analysis, X-ray diffractometry, nanoindentation, adhesion tests and friction tests were used to investigate the effect of arc current on surface morphology, composition, structure, and mechanical and tribological properties of coatings. It was found that all coatings present cubic AlCrN with Al/(Al+Cr) ratio independent on arc current. Increase in the arc current results in increase in lattice parameter, crystallite size as well as deposition rate and coating surface roughness. A decrease in hardness with a simultaneous increase in Young's modulus is also observed. The adhesion of the coatings shows a non-linear character with the maximum (108 N) for the coating formed at an arc current of 80 A, which may explain the best wear resistance – the lowest wear rate 1.4·10-7 mm3/Nm.

Wear-resistant ceramic coatings deposited by liquid thermal spraying

As a surface strengthening and surface modification technology of materials, liquid thermal spray technology has been used in many fields, such as wear and friction reduction, corrosion resistance, and high-temperature oxidation resistance. This article reviews the progress of liquid thermal sprayed coating in wear resistance as well as friction reduction in recent years. The influences of microstructure, composition, phase structure and mechanical properties on the tribological properties of typical coatings (including ceramic coatings and multiphase composite coatings) are investigated. The tribological properties of the coating are determined by the coating characteristics (including microstructure, porosity, mechanical properties, etc.) and the service conditions (working temperature, lubrication state, etc.). Typical ceramic wear-resistant coatings include Al2O3, YSZ, HA coatings, etc. The tribological properties of the coating can be significantly improved through process optimization and heat treatment. The comparison of nanostructured and microstructured ceramic-based coating reveals that nanostructured coating reduces wear by absorbing stress. The interaction between different constituent phases improves wear resistance and reduces wear in composite coatings. Finally, various challenges faced by liquid thermal spray are pointed out, and future research focuses are proposed.

Reverse Engineering of Mechanical and Tribological Properties of Coatings: Results of Machine Learning Algorithms

Reverse Engineering of Mechanical and Tribological Properties of Coatings: Results of Machine Learning Algorithms

Influence of film structure on the microstructure and properties of TiAlN coatings on Al-Si alloys

Due to the disadvantages of poor friction and low wear resistance, the application of Al-Si alloys with unique properties in pistons is limited. In this work, TiAlN ceramic coatings were prepared by filtered cathode vacuum arc technique to improve the surface properties of Al-Si alloys. To overcome the high residual stress of hard coatings growth on soft substrate surfaces due to interfacial mismatch and defect accumulation, gradient and multilayer film structures were adopted to improve adhesion strength. The effects of film structure on the microstructure, mechanical and tribological properties of coatings were systematically investigated. The results showed that the coatings with different film structures showed a multiphase microstructure with the dominated phase of TiAlN and a small amount of AlTi and TiN phases. Monolayer and multilayer coatings exhibited TiAlN (111) orientation, while the gradient coating showed (220) orientation due to the growth of columnar to equiaxed crystals. Compared with the monolayer coating, TiAlN coatings with gradient and multilayer structures had significantly reduced compressive stress and improved adhesion and scratch propagation resistance. Among them, the multilayer coating showed the lowest friction coefficient (~0.44) and wear rate (~5.14 × 10 −5 mm 3 /Nm), which were attributed to the high hardness (~31.01 GPa), toughness (H/E = 0.135, H 3 /E 2 = 0.563 GPa), critical load L C3 (~26.58 N). Interfacial effects in the multilayer structure could enhance synergy of the coating, thereby preventing crack initiation and propagation and adhesion failure. • TiAlN coatings with different structures were prepared on Al-Si alloys by FCVA. • Coatings were dominated by fcc TiAlN phase with less AlTi and TiN phases. • Adhesion of gradient and multilayer coatings were effectively improved. • Multilayer coatings showed the best mechanical and tribological properties.

Nanostructural glass composite coatings

The results of the study of glass-composite nanostructured self-lubricating coatings are presented. The developed glass composite is an antifriction material with an ultrafine structure. The structural components of these coatings significantly affect the graphitization process and provide an antifriction surface layer of α-graphite. The formation of this layer makes it possible to significantly minimize the contact parameters in the friction region.
 The developed antifriction nanostructured glass-ceramic self-lubricating coatings containing magnesium carbide and structural components that promote surface graphitization do not contain expensive and scarce components, meet environmental safety requirements, and have high performance characteristics. A significant effect of aluminoborosilicate in the form of a glass phase on the tribological properties of coatings is noted. An increase in adhesive strength is achieved by forming a surface layer of glassy sodium silicate. Using X-ray phase analysis, it was found that the intercalating elements in the subsurface zone-graphite system at the initial stage of the process were Mg2+, Al3+, Cu2+ ions, which randomly penetrated into the interlayer space of the graphite matrix. At sliding speeds of more than 3.0 m/s, intercalates of binary molecular compounds of these elements with oxygen were found in the layered system of graphite. Their intercalation is accompanied by a sequence of repetitive stages, which are reversible with a change in tribological parameters and are characterized by a specific transformation of the structure and, above all, by an increase in the distance between layers due to the influence of various types of interlayer defects and the introduction of intercalants.
 The presence of near-surface particles in the graphite layer does not affect the tribotechnical characteristics of the coatings. The developed glass-composite nanostructured self-lubricating coatings have high antifriction characteristics throughout the entire load-speed range