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316L stainless steel is used in a wide variety of corrosion-prone locations. However, its low hardness and poor tribological properties limit its application under heavy wear conditions. In this study, 316L Fe-based composite coatings co-doped with TB2 hard phases and rare-earth CeO2 exhibited excellent wear and corrosion resistance. Firstly, 316L-TiB2 cermet powder and (316L-TiB2)/CeO2 composite powder with high sphericity and density were prepared by high energy ball milling (HEBM), spraying drying granulation (SD), plasma spheroidization (PS) process. Then, 316L coatings, 316L-TiB2 and (316L-TiB2)/CeO2 cermet coatings were deposited by high velocity air fuel (HVAF) spraying. Finally, the effects of TiB2 and CeO2 additions on the microstructure, wear and corrosion behavior of the coatings were investigated. The results showed that TiB2 hard particles and CeO2 were uniformly distributed in the HVAF sprayed 316L-TiB2 and (316L-TiB2)/CeO2 coatings. The wear resistance of the coating prepared by 316L Fe-based composite powder with TiB2 and CeO2 is significantly improved. The hardness of the (316L-TiB2)/CeO2 composite coating was increased from 269 Hv0.3 to 826 Hv0.3 for the pure 316L coating, while the volumetric wear rate was only 3.6 % of that of the pure 316L coating (110 × 10−5 down to 4 × 10−5 mm3/N). Electrochemical tests show that the corrosion resistance of the coating decreases with the addition of TiB2 alone, but it can be improved by doping CeO2. The 316L Fe-based coating prepared by adding TiB2 and CeO2 can significantly improve the wear resistance of the coating, while the corrosion resistance decreases only slightly.

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. [ABSTRACT FROM AUTHOR]

Temperature control of mould surfaces is of high relevance for part quality in moulding processes. Due to highly dynamic heating behaviour, heating elements applied by thermal spraying can be an alternative to existing tempering methods. To ensure the feasibility of these heating coatings on industry‐relevant moulds, the coating system needs to be applied onto more demanding non‐flat geometries. For this purpose, the spray angle of the plasma spraying process is varied during the application of the titanium oxide/chromium oxide heating coating and the insulating aluminium oxide coating. Subsequently, the results are related to application‐oriented cavity shapes. Spray angle deviations from the optimal perpendicular angle are leading to decreasing dielectric strength of the coating system and an increase of the electrical resistivity. Additionally, the application efficiency reduces with the spray angle variation. Knowledge of the spray angle's influence on coating properties can help to coat more demanding shapes, including free formed surfaces or corners. [ABSTRACT FROM AUTHOR]

Ni-C abradable seal coatings were prepared by thermal spraying, and subjected to acid salt spray corrosion treatment for 192 hours. The microstructure, hardness, bonding strength, and abradability of Ni-C coatings before and after acid salt spray corrosion were explored. The research results indicated that the corrosion zone with thickness of 200-300 μm was formed on the top of Ni-C coatings after acidic salt spray corrosion. The average hardness of Ni-C coatings increased from 34.4 ± 3.2 HR15Y to 41.1 ± 2.4 HR15Y, and the average bonding strength of Ni-C coatings decreased from 14.6 ± 0.7 MPa to 13.3 ± 0.6 MPa. This is mainly due to the loss of soft materials such as graphite on the surface during the acidic salt spray corrosion, which leads to an increase in the surface average hardness. The poor bonding strength between the corrosion zone and uncorroded coating results in a decrease in bonding strength. The hardened corrosion layer is prone to peeling off during the wear-resistant scraping process, avoiding aggravating wear of dual blades due to the increased hardness of coating. The wear mechanism of Ni-C coatings has not undergo the significant change, remaining a mixed wear mechanism of plastic deformation and adhesive wear. [ABSTRACT FROM AUTHOR]

A solid-liquid composite lubrication coating capable of controlling friction and wear has received widespread attention among researchers. Here, a novel self-lubricating ceramic coating was created through a combination of thermal spraying, hydrothermal reactions, and vacuum impregnation. Its mechanical properties, tribological performance, and self-lubrication mechanism were thoroughly analyzed. The results indicate that the thermally sprayed ceramic coating contained carbon spheres and perfluoropolyether. As a result of the in-situ synthesis of carbon spheres, the coating exhibited enhanced mechanical properties. Compared to the single solid lubricant coating, the solid-liquid composite coating decreased the coefficient of friction by 46.7% to 0.112 and decreased the wear rate from 1.25 × 10−6 mm3/m N to 3.70 × 10−7 mm3/m N. It is proposed in this work that solid-liquid composite coatings can be prepared by utilizing the defects such as pores and microcracks inherent in thermal spray coatings for introducing solid lubricating phases and liquid lubricating phases. This strategy addresses the issue of degradation of the mechanical properties of conventional ceramic-based self-lubricating coatings due to their tribological design. [ABSTRACT FROM AUTHOR]

Enhancing the durability and extending the service life of concrete are crucial for promoting its sustainable development. Applying surface coatings is the primary technical method used to improve concrete durability. In this study, based on the plasma thermal spraying technology, a thermal-sprayed, ceramic-based coating was prepared on a concrete surface and evaluated using the drawing method, X-ray diffraction scanning electron microscopy with energy dispersive spectroscopy, X-ray computed tomography (X-CT), and frictional wear. Subsequently, performance tests were conducted. The test results showed that mullite powder was a suitable ceramic-based coating material. The coating had a good interfacial bonding ability with the concrete surface; moreover, the bonding site exhibited a chimeric state with an adhesion strength of 3.82 MPa. The wear rate of the coating material (0.02‰) is lower than that of the concrete matrix (0.06‰), resulting in improved surface wear resistance. SEM analysis reveals that the coating contains a considerable amount of amorphous or microcrystalline phases. The internal structure of the coating exhibits porous characteristics, with a total porosity of 10.35% and pore diameters predominantly ranging from 4 μm to 16 μm. At a distance of 80 μm from the coating site, the elements Al, O, and Si significantly contribute to the mullite components. The porous structures within the coating products are further verified using X-CT. This study offers a new possibility for ceramic coatings on hydraulic concrete. [ABSTRACT FROM AUTHOR]

With the development of human-cyber-physical-production systems in intelligent manufacturing, cyber-supported production based on artificial intelligence is becoming an increasingly powerful means of controlling machines and collaborating with human users. Semi-autonomous systems with a medium degree of automation enable human-centered, flexible, and sustainable production, for instance, in hybrid decision-making. Especially in applications that do not meet the requirements for full automation and when humans are to be involved in their role as qualified decision-makers, teaming-capable systems are desirable and offer considerable advantages. This paper outlines the transdisciplinary concept of human–machine teaming and the role of human cognition in engineering tasks with multi-criteria decision-making. An illustrative real-life example from thermal spray technology is used to show how explainable artificial intelligence models offer targeted, hybrid cyber decision support. This new approach based on fuzzy pattern classifiers combines expert knowledge- and data-based modeling and enables a transparent interpretation of the results by the human user, as shown here using the example of test data from atmospheric plasma spraying. The method outlined can potentially be used to provide hybrid decision support for a variety of manufacturing processes and form the basis for advanced automation or teaming of humans and cyber-physical-production systems. [ABSTRACT FROM AUTHOR]

In thermal spraying, molten YSZ (Yttria Stabilized Zirconia) drop impact is crucial to the understanding of formation of splats and hence coatings. However, existing studies hardly cast attention to the possible rebounding dynamics when successive molten YSZ drops impinge onto newly solidified splats whose temperature is still high so that freezing may be delayed. This work uses a newly developed numerical model based on the conservative level set method to probe into the rebounding dynamics of YSZ drops in practical thermal spraying conditions. The free-energy-based surface tension model in the phase field method was introduced to avoid the computing of curvature, which is however necessary in the continuum surface tension model. The projection method was invoked to solve the Navier–Stokes equations. The model was validated against an experiment of drop impact with rebounding, showing reasonable agreement. Moreover, the model was applied to both dense and hollow YSZ drop impact, with the details of fluid flow being analyzed. The maximum spread factor was found in agreement with existing scaling laws. [ABSTRACT FROM AUTHOR]

This study uses an air jet erosion tester to investigate the erosion behavior of NiCrAlY/Cr3C2/h-BN composite coatings that are plasma-sprayed at three different temperatures and 40 m/s on T22 boiler steel alloy. 30 and 90° are the impingement angles. To identify the erosion mechanism, SEM and X-ray diffraction techniques are used to analyze the surface morphology and phase generated on the eroded surface. Findings of erosion test indicate that the erosion resistance was notably enhanced by addition of Cr3C2 and h-BN because of its lubricating characteristics and capacity to reduce frictional forces during erosion. The combined influence of Cr3C2 and h-BN enhanced the coating hardness and erosion wear resistance, thereby improving its overall resistance to erosion. The weight loss method was employed to calculate the erosion rate, and the NiCrAlY/Cr3C2/h-BN coating showed up to 30.55% and 34.48% lower erosion rate as compared to uncoated T22 substrate at 600 °C for 30° and 90° impact angles, respectively. This characteristic is affected by the hard reinforcement Cr3C2's high-temperature stability, the h-BN's self-lubricating ability, the formation of a protective oxide layer that forms at 600 °C, and the eroded coating's ductile behavior of material removal. The study also reveals that the NiCrAlY/Cr3C2/h-BN coating system on T22 boiler steel alloy has excellent erosion resistance, making it suitable for use in high-temperature and erosive environments in boiler systems and similar industries.

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets.

NiCoCrAlY high entropy alloy (HEA) coating (47.1 wt.% Ni, 23 wt.% Co, 17 wt.% Cr, 12.5 wt.% Al, and 0.4 wt.% Y) was deposited on a stainless steel subtract by atmospheric plasma spraying (APS). The as-deposited coating was about 300 μm thickness with <1% porosity. The microstructure of the coating consisted of dispersed secondary phases/intermetallics in the solid solution. The stress–strain behaviour of this coating was investigated in micro-scale with the help of in situ micro-pillar compression. The experimental results show that yield and compressive stress in the cross-section of the coating was higher (1.27 ± 0.10 MPa and 2.19 ± 0.10 GPa, respectively) than that of the planar direction (0.85 ± 0.09 MPa and 1.20 ± 0.08 GPa, respectively). The various secondary/intermetallic phases (γ′–Ni3Al, β–NiAl) that were present in the coating microstructure hinder the lattice movement during compression, according to Orowan mechanism. In addition to that, the direction of the loading to that of the orientation of the phase/splat boundaries dictate the crack propagation architecture, which results in difference in the micro-mechanical properties. [ABSTRACT FROM AUTHOR]

The corrosion and wear resistance of aluminum-bronze coatings deposited by thermal flame spraying were investigated after a 10 h heat treatment at 500 °C in a nitrogen atmosphere. The coatings were characterized by SEM, EDS, XRD, and XRF. Corrosion resistance was evaluated by Tafel and EIS tests, while wear resistance was assessed using a ball-on-disc test. Results showed the heat treatment compacted the coating microstructure, increased oxide content, and improved splat bonding through diffusion mechanisms. This led to enhanced corrosion resistance, evidenced by reduced corrosion current density in electrochemical tests, resulting from densification impeding electrolyte penetration. Heat treatment also increased wear resistance, as indicated by lower wear rates in ball-on-disc tests, attributable to increased hardness, reduced friction coefficients, and annealing-induced microstructural changes. Overall, the heat treatment optimizes the anticorrosive and tribological properties of thermally sprayed aluminum-bronze coatings via favorable alterations in composition, morphology, and physical characteristics. The research provides a new understanding of how thermal spray parameters and post-deposition heat treatment can be utilized to enhance the corrosion and wear resistance of aluminum-bronze coatings for marine applications. [ABSTRACT FROM AUTHOR]

Achieving target coating thickness is one of the main objectives in thermal spraying. Despite this, there is a lack of measurement methods that could evaluate in situ the coating thickness with a sufficient accuracy that could be used as a robust feedback signal for online, closed-loop process control. This paper presents a novel approach for in situ spatially resolved coating thickness measurements. The measurement technique is based on a high-resolution 3D camera to capture the surface topography and include it in the thickness measurement. The technique provides results of total coating thickness with excellent accuracy when compared to the reference microscopical method. It also gives a 3D view of the coating thicknesses around the observed area as well as information about the thickness of individual coating layers. Moreover, the approach enables in situ evaluation of surface roughness, and a nondestructive estimation of coating porosity. [ABSTRACT FROM AUTHOR]

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets. [ABSTRACT FROM AUTHOR]

As one core component in hydrogen fuel cells and water electrolysis cells, bipolar plates (BPs) perform multiple important functions, such as separating the fuel and oxidant flow, providing mechanical support, conducting electricity and heat, connecting the cell units into a stack, etc. On the path toward commercialization, the manufacturing costs of bipolar plates have to be substantially reduced by adopting low-cost and easy-to-process metallic materials (e.g., stainless steel, aluminum or copper). However, these materials are susceptible to electrochemical corrosion under harsh operating conditions, resulting in long-term performance degradation. By means of advanced thermal spraying technologies, protective coatings can be prepared on bipolar plates so as to inhibit oxidation and corrosion. This paper reviews several typical thermal spraying technologies, including atmospheric plasma spraying (APS), vacuum plasma spraying (VPS) and high-velocity oxygen fuel (HVOF) spraying for preparing coatings of bipolar plates, particularly emphasizing the effect of spraying processes on coating effectiveness. The performance of coatings relies not only on the materials as selected or designed but also on the composition and microstructure practically obtained in the spraying process. The temperature and velocity of in-flight particles have a significant impact on coating quality; therefore, precise control over these factors is demanded. [ABSTRACT FROM AUTHOR]

Titanium alloys have long been esteemed for their exceptional mechanical properties and biocompatibility, making them a cornerstone material in various biomedical applications. However, to harness their full potential in implantology, orthopedics, and dentistry, biofunctionalization plays a pivotal role. This article provides a comprehensive exploration of the techniques and applications involved in biofunctionalizing titanium alloys.

Cavitation-resistant FeMnCrSi coatings were developed in the past years as a cost-effective alternative to Co-containing alloys to increase the lifespan of hydraulic machinery. The effect of different chemical compositions, surface finishing, and post-processing treatments was investigated for various processing techniques, namely: Arc Spraying Process (ASP), High-Velocity Oxy-Fuel (HVOF), High-Velocity Air-Fuel (HVAF), Plasma Transferred Arc (PTA), and Cold Gas Spray (CGS). This works consists of a compilation and review of original and literature results, and discusses the microstructure changes imparted by each type of processing and their impact on the coating properties and cavitation resistance. Low heat input high-velocity processes (HVOF, HVAF, CGS) developed a reduced degree of oxidation and porosity, accounting for a cavitation resistance higher than that of the coatings that ASP processed. In addition, ASP coatings showed reduced cohesive strength, with the oxidized inter-splat interface being a preferential site for crack propagation.

Offshore wind power is a kind of green energy, which has attracted more and more attention. The anti-corrosion technology of offshore wind power facilities has become a current research hotspot. This paper first expounded the corrosion mechanism of equipments in the marine environment, and then introduced the commonly used anti-corrosion technologies for offshore wind power facilities, including the anti-corrosion coatings, cathodic protection, reserved corrosion allowance method, etc. Then, combined with an example, the anti-corrosion technology of thermal spraying and mineral grease coating in the new anticorrosion method in splash area were introduced emphatically. Finally, it briefly described the anti-corrosion detection and maintenance means of wind power facilities. It also introduced the corrosion protection methods used in Guishan wind power project in Zhuhai, Guangdong, which has been built into grid connected power generation in China, in order to provide some suggestions for improving the anti-corrosion level of offshore wind power.

To protect materials from abrasion-corrosion, various thermal spraying methods can be used to apply coatings, such as gas-flame powder spraying, plasma spraying, high velocity oxygen-fuel spraying and detonation cannon. Thermal spraying is one of the most effective methods of protecting the material from wear and corrosion, thereby increasing the service life of the material used. We present the surface modification of coatings based on Ni-Cr-Al by a pulsed plasma treatment using a plasma generator. The coatings were obtained by detonation spraying followed by pulsed plasma treatment. The changes to the structural properties of the coatings under the influence of plasma flow were studied using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The mechanical and tribological properties were analyzed by surface roughness characterization, microhardness testing and tribological tests for a comprehensive analysis of changes in the characteristics of the Ni-Cr-Al coatings following pulsed plasma treatment. It was found that modification of the coating by pulsed plasma treatment causes an increase in the microhardness of the surface layer, as well as a reduction in the surface roughness and friction coefficient. According to the results of X-ray phase analysis, these improvements in the mechanical and tribomechanical properties of the obtained surfaces is associated with an increase in the content of CrNi3, NiAl and NiCr phases in the coatings.

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.

Robot-assisted spraying is a widespread manufacturing process for coating a multitude of mechanical components in an efficient and cost-effective way. However, process preparation is very time-consuming and relies heavily on the expertise of the robot programmer for generating the appropriate robot trajectory. For this reason, industry and academia investigate the possibility of supporting the end-user in the process by the use of appropriate algorithms. Mostly partial concepts can be found in the literature instead of a solution that solves this task end-to-end. This survey paper provides a summary of previous research in this field, listing the frameworks developed with the intention of fully automating the coating processes. First, the main inputs required for the trajectory calculation are described. The path-generating algorithm and its subprocesses are then classified and compared with alternative approaches. Finally, the required information for the executable output program is described, as well as the validation tools to keep track of program performance. The paper comes to the conclusion that there is a demand for an autonomous robot-assisted spraying system, and with a call-for-action for the implementation of the holistic framework. [ABSTRACT FROM AUTHOR]

We investigated the wear and corrosion properties of high-velocity oxygen fuel (HVOF)-sprayed microstructured and near-nanostructured WC-17 wt. % Co coatings fabricated on steel substrates. The near-nanostructured variant exhibited a high hardness value of ~991 Hv, a low corrosion rate of ~0.10624 MPY, a low wear rate of ~0.0012 mm3/m, and a low cumulative wear volume loss of ~0.1304 mm3. Corrosion effects resulted in a reduction of hardness by 23.02% and 30.07% for the near-nanostructured and microstructured samples, respectively; moreover, the wear volume loss of the microstructured coating was 30.02% higher compared to the near-nanostructured coating. We attribute the enhanced corrosion and wear resistance of the near-nanostructured HVOF coating to its dense and uniform surface morphology, low porosity, minimal decarburization, and high hardness. Triboscopic imaging studies further confirmed a low degradation rate, high wear resistance, and minimal wear volume loss. [ABSTRACT FROM AUTHOR]

The study of the structural-phase state and tribotechnical properties of antifriction gas-thermal coatings made of aluminum alloy AlSi12, welding bronze CuSi3Mn1, as well as composite material CuSi3Mn1 + AlSi12 and a coating of bronze CuSn10P1 obtained by centrifugal induction surfacing was carried out. It is shown that composite gas-thermal coatings from CuSi3Mn1 + AlSi12 after spraying include Cu, Al, Cu9Al4, CuAl2, Cu3Al, Si, and Al2O3 phases. The matrix phase of the bronze interlayers is doped with aluminum, while the Al interlayers are doped with copper. It has been established that annealing of coatings CuSi3Mn1 + AlSi12 at temperatures of 175 and 225°С for 2 h leads to the release of an additional amount of intermetallic compounds in them and an increase in their microhardness. It is shown that composite gas-thermal coatings have ≈1.2–1.7 times higher wear resistance in the environment of I-20A and Litol-24 lubricants compared to coatings of CuSn10P1 bronze. Annealing of composite coatings from CuSi3Mn1 + AlSi12 leads to an increase in their wear resistance in the environment of I-20A liquid lubricant up to 30% and Litol-24 up to 20% compared to the initial state. The coefficients of friction of all antifriction coatings based on copper in the environment of the I-20A lubricant did not exceed 0.08, and in the environment of the Litol-24 lubricant, 0.10. [ABSTRACT FROM AUTHOR]

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Coatings from WC–Co–Cr AMPERIT®554.074 powder were deposited using a multichamber detonation device. Investigations of coating microstructure and phase composition were conducted, using scanning electron microscopy and X-ray structural analysis. Dense coatings form at spraying by this method which consist of inclusions of tungsten carbide phases, uniformly distributed in Co–Cr matrix. Coating porosity is equal to ~0.2 %, microhardness is – 10.4 ± 1.2 GPa. Experience of application of multichamber detonation device for deposition of wear-resistant coatings from WC–Co–Cr powder is shown, both at the stage of part reconditioning and at design of components of various mechanisms. [ABSTRACT FROM AUTHOR]

To protect materials from abrasion-corrosion, various thermal spraying methods can be used to apply coatings, such as gas-flame powder spraying, plasma spraying, high velocity oxygen-fuel spraying and detonation cannon. Thermal spraying is one of the most effective methods of protecting the material from wear and corrosion, thereby increasing the service life of the material used. We present the surface modification of coatings based on Ni-Cr-Al by a pulsed plasma treatment using a plasma generator. The coatings were obtained by detonation spraying followed by pulsed plasma treatment. The changes to the structural properties of the coatings under the influence of plasma flow were studied using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The mechanical and tribological properties were analyzed by surface roughness characterization, microhardness testing and tribological tests for a comprehensive analysis of changes in the characteristics of the Ni-Cr-Al coatings following pulsed plasma treatment. It was found that modification of the coating by pulsed plasma treatment causes an increase in the microhardness of the surface layer, as well as a reduction in the surface roughness and friction coefficient. According to the results of X-ray phase analysis, these improvements in the mechanical and tribomechanical properties of the obtained surfaces is associated with an increase in the content of CrNi3, NiAl and NiCr phases in the coatings. [ABSTRACT FROM AUTHOR]

Coatings from wC-Co-Cr amperIt®554.074 powder were deposited using a multichamber detonation device. Investigations of coating microstructure and phase composition were conducted, using scanning electron microscopy and X-ray structural analysis. Dense coatings form at spraying by this method, which consist of inclusions of tungsten carbide phases, uniformly distributed in Co-Cr matrix. Coating porosity is equal to ~0.2 %, microhardness is 10.4 ± 1.2 GPa. Experience of application of multichamber detonation device for deposition of wear-resistant coatings from WC-Co-Cr powder is shown, both at the stage of part reconditioning and at design of components of various mechanisms. [ABSTRACT FROM AUTHOR]

Refractory metals such as molybdenum, tantalum, tungsten, niobium and their alloys have the characteristics of high melting point and good high temperature performance, which play a major role in the field of protection. However, due to their high cost, high melting point, low thermal conductivity and high brittleness, their processing is relatively difficult. By using specific processes to prepare refractory metal coatings on the substrate surface to achieve excellent mechanical properties and high-temperature performance of refractory metals without changing the substrate properties, and effectively reduce manufacturing costs, which has significant research value for equipment surface protection. Because the refractory metal coatings play an increasingly important role in the manufacturing industry, the plasma spraying, explosive spraying, laser cladding and cold spraying preparation technology of molybdenum, tantalum, tungsten, niobium and other refractory metal coatings were introduced firstly, and the characteristics of each process were summarized. On this basis, the microstructure and properties of refractory metal coatings prepared by different processes were analyzed and compared, and the improvement progress was summarized from three aspects of coating material composition and structure, process parameters and post-treatment. Finally, the existing problems and development directions of the refractory metal coating preparation technology were prospected.

In this study, finite element method is applied to simulate thermal spraying of Stellite-6 microparticles on steel substrate. The effects of particle size, substrate pre-heating temperature and spraying angle are investigated on the process output parameters including stress, equivalent plastic strain, penetration depth, and temperature distribution. The simulations are designed and performed based on the Design of Experiments (DOE). Response surface methodology (RSM) is used to explore the relationships between the input factors and responses. The simulation results revealed that penetration depth as the main factor, affecting the bonding strength of coating, is highly dependent on the particle size. Spraying angle is also found to be a significant and effective parameter on the penetration depth. On the other hand, the pre-heating temperature of the substrate is observed to have no substantial effect on the penetration depth.The depth of penetration increases with increasing the particle size and spraying angle, and reaches its maximum value in spraying angle of 90˚.

In the field of surface engineering, thermal spraying is very wide adopted in many branches of the industry. The main reasons of such situation are its flexibility as well as cost effectiveness. Among others, High Velocity Oxy Fuel (HVOF) technique is dedicated for spraying hardmetal and cermet coatings, especially for wear- and corrosion resistance. Such type of coating could be a promising candidate as protective layer for magnesium alloys elements. These materials need a strong improvement in the corrosion protection as well as on the field of wear resistance in order to be widely used in the industry. In this work, different WC-based coatings, namely: (i) WC-Co, (ii) WC-Co-Cr and (iii) WC-Cr3C2-Ni manufactured by HVOF spraying, were investigated. The form of all feedstock materials was agglomerated and sintered powder. All coatings were sprayed with the same technological parameters, especially spray distance which was equal to 400 mm on the AZ91 magnesium alloy substrate. The main aim of the studies was to investigate the influence of the powder material on the corrosion resistance of obtained coatings. The manufactured coatings were examined in terms of its microstructure, using scanning electron microscope (SEM) and corrosion performance, which was assessed in the electrochemical corrosion investigations in 3.5% NaCl solution by Tafel method. The study showed that the corrosion resistance increasing in such order: AZ91 < WC-Cr3C2-Ni < WC-Co < WC-Co-Cr. It should be stressed that WC-Cr3C2-Ni coating exhibits very low corrosion performance, which could be effected by relatively high porosity (c.a. 3 vol.%) and because of that the more complex composition promotes creation of many corrosion cells.

In this work, the tribological behaviour of thermally sprayed titanium and chromium ceramic-based coatings was investigated under abrasive conditions. Their structure was studied by a scanning electron microscope (SEM), while their hardness was evaluated using a microhardness tester. To study the strength of these ceramic coatings under abrasion conditions, reciprocating sliding experiments were carried out in a high-precision (10 mN resolution, 1000 Hz data acquisition) pin-on-disk apparatus and by using a Ø6 mm corundum ball to generate high contact pressures (1.5 GPa). To thoroughly investigate the friction evolution of the tribo-system, three-dimensional mapping of the tangential friction forces (triboscopy) was performed. Following the abrasion experiments, the wear of these coatings was measured using confocal microscopy. The obtained friction and wear results were compared to state-of-the-art materials and coatings that are currently being used in various industrial applications. From this comparison, it was found that the titanium and chromium ceramic-based coatings have comparable if not better tribological properties for the given conditions. The main wear mechanism was mainly two-body abrasion due to the surface roughness of the counter-material, as well as three-body abrasion due to the formation of debris at the interface.

NiCoCrAlY high entropy alloy (HEA) coating (47.1 wt.% Ni, 23 wt.% Co, 17 wt.% Cr, 12.5 wt.% Al, and 0.4 wt.% Y) was deposited on a stainless steel subtract by atmospheric plasma spraying (APS). The as-deposited coating was about 300 μm thickness with 3Al, β–NiAl) that were present in the coating microstructure hinder the lattice movement during compression, according to Orowan mechanism. In addition to that, the direction of the loading to that of the orientation of the phase/splat boundaries dictate the crack propagation architecture, which results in difference in the micro-mechanical properties.

This article presents the results of a study of a composite coating made of ultrahigh molecular weight polyethylene (UHMWPE) with a diabase filler obtained by flame spraying. Diabase of 10 wt.%, 20 wt.%, 30 wt.% and 40 wt.% was chosen as a filler. The polymer coating was applied to the St3 metal substrate using temperature control in a conventional flame spraying process. The coating was studied using scanning electron microscopy, X-ray phase analysis, infrared spectroscopy, abrasive wear resistance, microhardness testing and determination of the friction coefficient. It has been shown that diabases do not have a negative effect on the initial chemical structure of UHMWPE and it is not subjected to destruction during flame spraying. The introduction of diabase into the composition of UHMWPE with a content of 10–40% of the total mass does not adversely affect the crystalline structure of the coating. It has been established that with an increase in the volume of the diabase filler, the wear resistance of the composite coating based on UHMWPE increases. It has been determined that with the addition of diabase, the microhardness of the coatings increases. [ABSTRACT FROM AUTHOR]

The wear and corrosion resistance of an Fe54Mo9Cr15C6P2Si2B3W9 amorphous metallic coating deposited on the C45 steel by twin wire arc-spraying process were evaluated through friction and wear tests and electrochemical measurements. The experimental results indicated that the amorphous metallic coatings had clearly better wear resistance than substrate, mainly exhibiting abrasive wear mechanism behavior, which was totally different from that of substrate. Corrosion resistance of the C45 steel was effectively improved due to the presence of amorphous metallic coating since the coating increased corrosion potential and decreased corrosion current density of substrate. Additionally, the coating possessed larger impedance than substrate even after long-term immersion, which was mainly attributed to the unique structure mostly composed of amorphous phase and less grain boundaries effectively hindering inward penetration of corrosive substances. The current amorphous metallic coating prepared by twin wire arc-spraying technology had potential application in protection field of carbon steels. [ABSTRACT FROM AUTHOR]