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To improve the corrosion resistance of mechanical components, cold sprayed assisted laser remelting was used to synthesized HEA coatings with different Co contents AlCoxCrFeNiCu(x = 0,0. 5,1,1. 5,2). The effects of the change in Co content on the phase structure, microstructure and corrosion resistance of the alloy coating was characterized via XRD, SEM, EDS, TEM, electrochemical test system and other equipment tests. The results show that the laser remelting AlCoxCrFeNiCu HEA coatings is composed of simple BCC and FCC phases, when x=1, the lattice distortion of HEA coatings is the largest, with the increase of Co content, the equiaxed dendrites of the laser remelting AlCoxCrFeNiCu HEA coatings become less and more and gradually refine, and the spacing of columnar dendrites first increases and then decreases. In 3. 5% NaCl corrosive medium, when x = 0. 5, there is slight segregation of Cu element in HEA coatings, and a small amount of pitting occurs. The laser remelting synthesized AlCo0.5CrFeNiCu HEA coatings has the most positive self-corrosion potential, the corrosion current density reaches the minimum, the corrosion rate was 2. 28×10-3 mm/a, the AlCo0.5CrFeNiCu HEA coating shows good corrosion resistance. [ABSTRACT FROM AUTHOR]

The electrical contact is a pivotal component in the power transmission system, whose failure mode is closely related to the wear property of the coating on it.In this work, the silver coating was prepared by air supersonic flame spraying and cold spraying(CS).Subsequently, the reciprocating friction test was used to study the friction and wear properties of the coatings under different loads and frequencies, and the results were compared with the property of coatings fabricated by using electroplating.The scanning electron microscope(SEM)and X-ray energy spectrometer(EDS)were used to investigate the morphology and composition of the worn surface, and the friction and wear mechanisms of the coatings were analyzed and discussed.Results showed that both air supersonic flame spraying and CS processes could prepare thicker and denser silver coatings.The silver coatings prepared by cold spraying presented higher microhardness, smaller friction coefficient and lower wear loss under the high frequency and high load conditions.Besides, the wear mechanism of silver coating prepared by air supersonic flame spraying and CS was mainly fatigue wear.

High - entropy alloys are a kind of novel multi - principal component alloy that recently breaks through the design concept of traditional alloys, which were significantly superior to conventional metallic materials in compressive strength, hardness, thermal stability, wear resistance and corrosion resistance. Meanwhile, cold spray is a solid - state deposition technology, attracting great attention around the world in preparing high - performance coatings, repairing, and remanufacturing parts, and additive manufacturing parts and components, which could provide a new approach for preparing high - entropy alloys. In this work, by analyzing the research status of cold spraying high entropy alloy at home and abroad, the recent progress of cold spraying high - entropy alloys was reviewed from feedstock powders preparation, spraying process parameter optimization, microstructure and properties of coating, particle bonding mechanisms, and post - treatment processes. Besides, the future research direction of cold spraying high performance high - entropy alloys was also prospected.

At present, the research on low - pressure cold sprayed Al - Al2O3 composite coating mainly focused on the process and properties, and there was less research on the deposition characteristics and mechanism of particles. For this, the Al - Al2O3 composite coating was deposited by low pressure cold spraying technology (LPCS). The effects of different carrier gas temperatures on the deposition characteristics of the composite coating were studied. The thickness, surface morphology and microstructure of the composite coating were analyzed by scanning electron microscope (SEM) and three - dimensional profiler. Results showed that the thicknesses of Al - Al2O3 composite coating prepared by LPCS at different carrier gas temperatures (300, 400, 500 and 600 ℃) were 213.34, 321.62, 920.64, 986.97 μm, respectively. The thickness of composite coating increased with the increase of carrier gas temperature. Especially when the carrier gas temperature of cold spraying increased from 400 ℃ to 500 ℃, the thickness of deposited coating was increases by 186.25%. The maximum height difference Hmax and roughness Ra of the composite coating surface increased with the increase of carrier gas temperature. When the carrier gas temperature was 400 ℃, the surface quality of the composite coating was the best. When the carrier gas temperature rose from 400 ℃ to 500 ℃, the increased amplitudes of Hmax and Ra were the largest, 72.68% and 52.22%, respectively. The surface quality of the composite coating decreased with the increase of carrier gas temperature. The flattening rate of deformed Al particles in the composite coating decreased with the increase of carrier gas temperature. Al particles in the composite coating gradually changed from flat shape with large plastic deformation (300 ℃) to ellipsoid shape with small plastic deformation (600 ℃). The sudden increase of deposition rate of Al - Al2O3 coating and the decrease of particle flattening rate with the increase of carrier gas temperature were attributed to thermal softening effect of Al particles.

The porosity of the cold sprayed deposits reflects the deformation degree of the sprayed particles and the bonding degree between them, which has an important influence on the deposit properties such as hardness, elastic modulus, friction and wear performance, corrosion resistance, fatigue property and so on. Hence, the porosity of deposits is very important for evaluating the comprehensive properties of deposits and optimizing the cold spraying process parameters, and it is one of the important indicators to evaluate the quality of deposits. Although previous review articles have summarized the influence of cold spraying process on the cold sprayed deposits performance, there were few review articles involving pores in cold sprayed deposits and their control methods. Referring to dozens of articles, this article aimed to review the formation of pores in cold sprayed deposits, the measurement methods, the influence factors and summarize the influence of porosity on the properties of deposits and the measures to reduce the porosity of deposits.

In order to promote the application of cold spray technology in the field of aviation protective coatings, this work prepared CuNiIn coating on surface of TC4 titanium alloy via cold spray with nitrogen technology. The macrostructure and microstructure, microhardness and fretting wear properties of the coating were analyzed by optical microscope, scanning electron microscope, microhardness tester and fretting wear tester respectively. Results showed that the overall porosity of the coating was about 2.8%, and the closer to the substrate, the denser the coating. The microstructure of the coating was finer than that of the original powder. Moreover, the hardness value of the coating increased from the substrate to the surface along the thickness direction, which changed from 274 HV2 N of average hardness near the substrate to stable value of 300 HV2 N near the surface of the coating. When the fretting displacement was small, the coating failure mechanism was mainly adhesive wear, and the wear morphology was oval. When the fretting displacement was large, it was mainly abrasive wear, and the wear morphology was close to circular.

Cold spray, as a low - temperature solid - state forming technology, has a series of advantages over other deposition methods, such as little heat influence towards substrate, minimized particle oxidation, and high deposition efficiency, and therefore it has been widely used for metallic protective coating fabrication, component repair and additive manufacturing. In this work, the characteristics of cold spray were firstly demonstrated from three aspects including cold spraying system, materials, and process. Next, the research progress of cold spraying technology on powder materials design, coating bonding mechanism, and coating microstructure and performance control in recent years were presented. Then, the application of cold spraying technology in the field of foreign naval ships and warships was described in detail. Finally, the research and application of cold spraying technology in the field of naval ships and warships in China were briefly described, and its future development direction was prospected in order to improve the corrosion protection and maintenance support ability of naval ships and warships equipment in China.

A layer of pure aluminum coating was prepared on AZ80 magnesium alloy by cold spray, and then a pure aluminum/aluminum oxide composite coating was successfully fabricated on the surface of pure aluminum coating by micro-arc oxidation. The surface and cross-section morphology, composition and phase structure of the coatings were analyzed by scanning electron microscope (SEM), energy spectrometer (EDS) and X-ray diffractometer (XRD). The corrosion behavior of the coatings immersed in 3.5%NaCl(mass fraction) solution for different time (30 min and 7 days) was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results show that after 30 minutes of immersion, the corrosion current densities of the pure aluminum coating and the pure aluminum/aluminum oxide composite coating are 3.7×10-6 A·cm-2 and 8.0×10-7 A· cm-2, respectively; after 7 days of immersion, the corrosion current densities are 9.0×10-6 A·cm-2 and 1.8×10-6 A·cm-2, respectively. Both the pure aluminum/aluminum oxide composite coating and the cold sprayed aluminum coating can effectively delay the corrosion of the magnesium alloy substrate. Among them, the corrosion resistance of the micro-arc oxidation composite coating is nearly 5 times of the cold sprayed pure aluminum coating. The further improvement in corrosion resistance is attributed to the excellent physical barrier effect of the micro-arc oxidation ceramic layer.

The iron-based amorphous alloy powder was subjected to cyclic cryogenic treatment to enhance the ability of plastic deformation, and coatings were deposited on substrate materials with different hardness, including AZ31B magnesium alloy, 6061 alu minum alloy and Q235 carbon steel. The effect of cryogenic treatment on the cold spray deposition behavior of iron-based amorphous powder on different substrate materials was studied. The interfacial bonding state between coatings and substrate materials, the friction and wear properties of cold sprayed coatings were comprehensively evaluated. Results show that the hardness, thermal conductivity and elastic modulus of the substrate will affect the strain condition, heat dissipation rate and rebound energy of the particles, and then affect the deformation state, compactness and deposition efficiency of the coating. The cryogenic treatment improved the deposition efficiency of amorphous particles, resulting in a great increase of coating thickness. With the increase of hardness of substrate materials, the friction coefficient of substrates and coatings increased, and the wear loss reduced. Compared with the substrate, amorphous alloy particles effectively inhibited the cutting action of the grinding ball, leading to the decrease of the friction coefficient and mass loss of original amorphous coating. Tn comparison, amorphous coatings made of cyro-processed powders had higher density, the friction coefficient curve was more stable and the mass loss was further reduced. The wear mechanism of magnesium alloy matrix and the amorphous coating is abrasive and oxidative wear. The wear mechanism of alu minum alloy matrix is adhesion, fatigue and oxidative wear, while abrasive and oxidative wear are observed in the amorphous coating. The wear mechanism of carbon steel matrix and the amorphous coating is fatigue and oxidative wear. [ABSTRACT FROM AUTHOR]

In order to form ts own characteristics m the research fields of new metal material, material surface modification, nano-coating, additive manufacturing, and high-value use of rare earths, expand application range of cold spray technology, and promote cold spray coatings, repair layers and additive components are more widely used. Based on research of imported cold spray system design principles and material science, the deposition mechanism of cold spray system was analyzed, and a variety of key technologies for preparation of new cold spray coatings with unique properties were explored and developed, which Include cold spray preparation technology of Cu- Fe in-situ alloy foil,new Cu-Fe alloy thermal and magnetic coating,Cu/Fe composite material/parts,and lanthanum oxide doped aluminium-TO composite functional coatings technologies. Cold spraying technology can obtain uniform,dense and oxide-free coating, which is suitable for deposition information of all metals and their alloys, repair of parts, and additive manufacturing. It is also suitable for a variety of ceramic coatings and organic coatings. The preparation of polymer coatings, composite coatings and nam-coatings has become an effective means for research and development of amorphous, nano-and new-type composite coatings. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nickel aluminum bronze is the main material used to cast large ship propellers. However, marine biofouling on the surface of the propeller alters the pH value, thereby accelerating tribocorrosion and threatening ship safety. In this study, a compact nickel aluminum bronze coating with a thickness of approximately 300 μm was deposited by cold spraying. The microstructure of the coating was observed by scanning electron microscopy and optical microscopy. The electrochemical corrosion properties and tribocorrosion behavior of the coating was determined using 3.5% NaCl solution in different pH environments of 3, 7, and 11. Results show that in a pH 3 environment, optional corrosion occurs on the nickel aluminum bronze substrate, cracks mainly containing Cu are mostly distributed on α phases, deep cannelure is observed on the wear trace of the coating, and abrasive wear occurs on the coating. In a pH 7 environment, adhesive wear occurs on the substrate, slice abrasive dust is distributed on the surface of wear trace of the substrate (because porosities on the coating absorb most of the abrasive dust and avoid three body friction), cannelure on the coating is relative shallow. In pH 11 environment, surface fatigue occurs on the surface of the substrate and deep cannelure is observed on the wear trace of coating, which contains cracks. Generally speaking, tribocorrosion resistance of coating enhances during cold spray process in different pH environments, resulting from cold working hardening and abrasive dust entering the coating pores.

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

CoNiCrAlY coatings were prepared by cold spray process. After deposition, the pre-oxidation treatment of the coating was performed by vacuum heat-treatment. The microstructure and phase constituent of coating were characterized by XRD, SEM and EDS. The hot corrosion behavior of as-sprayed and pre-oxidized CoNiCrAlY coatings in molten Na2SO4 at 900℃ was also studied. The results show that the as-sprayed coating presents a dense structure with low porosity (less than 0.28%, volume fraction) and low oxygen content (0.12%, mass fraction). Vacuum pre-oxidation treatment forms a continuous and dense α-Al2O3 layer on the coating surface, with an average thickness of about 0.26μm. As-sprayed and pre-oxidized coatings can protect the substrate from hot corrosion due to the formation of a continuous and dense α-Al2O3 layer. Moreover, the vacuum pre-oxidation treatment can alleviate the diffusion of S and O into coating, and thus the hot corrosion resistance of coating is improved. The damage of hot corrosion plays a more important role than high temperature oxidation. When corrosion in single Na2SO4 molten salt with the same temperature, the consumption speed of Al is two times of that in high temperate oxidation

The 3D simulation of Cu particles impacting on medium steel substrate in the laser-assisted cold spray process is performed using the finite element analysis software ANSY/LS-DYNA based on Johnson-Cook material model and bilinear isotropic hardening material model. The process parameters, such as particle impact velocity, deposition temperature, are simulated to obtain the deformation contours, crater depth and so on. The results show that Cu particles can be deposited on medium steel effectively at the velocity of 800 m/s in room temperature environment and at the velocity of 500 m/s at 850 °C. In addition, the two material models both can be used to predict the process parameters for the laser-assisted cold spraying. [ABSTRACT FROM AUTHOR]

To shorten the research and development period and to lower the complex of design of cold spray system, a commercial software Star-CCM + (Version 6.04) is used to calculate the state of gas flow, the relationship between exit temperature and the structure of gas heater, flow rate and heat input. The results indicate that a steady temperature can be reached for the whole gas heater. The velocity of the gas changes little in the tube. There exists a large temperature difference between resistance tube and the gas. An optimized heater structure can increase the efficiency of heat exchanging. To ensure a high efficiency, the length of the resistance tube must be long enough; the larger the center pitch, the higher the exchange efficiency. The suitable diameter (8-12 mm) is also required for the resistance tube. [ABSTRACT FROM AUTHOR]