超音速激光沉积WC/SS316L复合涂层微观结构及磨损性能研究

采用超音速激光沉积和冷喷涂技术,在碳钢基体上制备了WC/SS316L复合涂层,利用金相显微镜、扫描电子显微镜、能量色谱仪、摩擦磨损试验机对超音速激光沉积及冷喷涂复合涂层的微观结构、成分及磨损性能进行了对比研究。结果表明:在沉积温度为800℃下制备的超音速激光沉积涂层的沉积效率和WC含量较冷喷涂涂层分别提高了43%和30%,其涂层致密性也优于冷喷涂涂层;超音速激光沉积涂层的摩擦系数比冷喷涂涂层低19%,表现出较优的抗磨损性能。     

Pulsed Laser Deposition of Boron Carbon Nitride Coatings

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Microstructure and Phase Composition of Ni-Based Alloy Obtained by High-Speed Direct Laser Deposition

Phase composition and structural features of nickel-based alloy EP741 obtained by high-speed direct laser deposition were discussed in the paper. The technology of high-speed direct laser deposition has been successfully applied during the formation of samples with the various operating parameters of the experimental device. The laser power was between 450 and 1200 W, the scanning speed was 1.2 mm/s, the powder feed rate was 45 g/min, and the laser beam diameter was 1.2 mm. The structure and phase composition of the initial material and as-deposited samples were studied using optical and scanning electron microscopy, x-ray analysis and transmission electron microscopy. The investigation has shown that spherical particles of powder (EP741) can be used to form products by additive manufacturing with the presence of additional heat treatment, since almost all the as-deposited samples obtained do not contain cracks, and large volume of pores was observed only in the sample obtained with the power of 450 W. In addition, the phase composition of the as-deposited samples showed a high content of precipitating phase Ni₃(Al, Ti) in matrix, which is coherent to the solid solution based on nickel. In theory, the presence of Ni₃(Al, Ti) phase corresponds to the heat-treated nickel-base alloy obtained by standard methods of processing.     

化学沉积Co-Fe-P纳米涂层结构与磁学性能研究

本文采用化学沉积的方法,在板状基体上成功的制备纳米晶Co-Fe-P合金涂层。运用TEM、XRD等分析手段对[Fe^2 ]对Co-Fe-P合金成分、结构、性能的影响进行分析研究。结果表明合适工艺参数的调整选择,可获得表面光亮致密与基体结合良好的纳米晶Co-Fe-P化学沉积膜,且所得纳米晶Co-Fe-P合金具有较低的矫顽力和较高的矩形比,可以用作软磁材料。     

Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface (R _a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness (R _a of 5.7 μm), low porosity (0.8%), excellent mechanical properties (H _it = 6.1 GPa, E _it = 155 GPa), and elevated interface toughness (2.4 MPa m^1/2).     

Wear-Resistant and Anticorrosive Coatings Based on Chrome Carbide Cr7C3 Obtained by Electric Spark Deposition

Protection of Metals and Physical Chemistry of Surfaces - This work is devoted to the deposition of Cr3C2 chromium carbide powder on steel 35 by electrospark treatment in titanium granules. Three...     

Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle–substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.     

Platinum and Iridium Coatings Obtained by Double Glow Plasma Technology

Pt and Ir coatings were produced by double glow plasma technology on the surface of Ti alloy substrates. The chemical compositions of the coatings were determined by X-ray diffraction and X-ray photoelectron spectroscopy. The microstructure and morphology of the coatings were observed by scanning electron microscopy. The hardness and elastic modulus of the coatings were estimated by nanoindentation. The measurements of adhesive forces of the coatings were performed with scratch tester. The results indicated that the Pt and Ir coatings displayed the preferred (220) orientation due to the initial nuclei with preferred growth on the surface of the substrates. The interface between the Pt coating and substrate exhibited no evidence of delamination. The Ir coating was composed of irregular columnar grains with many nanovoids at the interface between the coating and substrate. The mean values of hardness for Pt and Ir coatings were 0.9 GPa and 9 GPa, respectively. The elastic modulus of Pt and Ir coatings were 178 GPa and 339 GPa, respectively. The adhesive forces of the Pt and Ir coatings were about 66.4 N and 55 N, respectively. The Pt and Ir coatings adhered well to the Ti alloy substrates.     

Microstructures and Dielectric Properties of PZT Coatings Prepared by Supersonic Plasma Spraying

This paper studied the microstructures and dielectric properties of PZT coatings prepared by supersonic plasma spraying. Samples of the PZT coatings were evaluated by various techniques. The phases and microstructures of the coatings were investigated by XRD, SEM, and TEM, respectively. The results showed that the coatings deposited on steel substrate had a dense microstructure, and there was no phase transformation during spraying. Additionally, the Curie temperature of the PZT coatings was about 370 °C by the investigation of dielectric constant.     

超音速等离子喷涂NiCr-Cr3C2工艺的参数优化

采用四因素三水平正交试验,通过在线监测喷涂粒子的温度和速度,对电流、电压、喷涂距离和主气流量四个超音速等离子喷涂的主要参数进行优化设计.结果表明:四个因素对喷涂粒子温度的影响均较大,电压和主气流量对喷涂粒子速度的影响较大;优化的工艺参数为电压150 V、电流400A、喷涂距离85 cm、氩气流量4.2m3/h,采用该优...     

Photocatalytic Activity of Nanostructured Anatase Coatings Obtained by Cold Gas Spray

This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS) supported on titanium sub-oxide (TiO_2?x ) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO₂ particles fragmented when impacting onto the hard surface of the APS TiO_2?x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO₂ coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25^® photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide.     

WC-Co/Al Multilayer Coatings by Warm Spray Deposition

WC-Co/aluminum multilayer coatings have been developed by using warm spray deposition to improve fracture toughness and damage tolerance of conventional WC-Co coatings and to investigate the effects of ductile layer addition on their fracture properties. Prior to depositing the multilayer coatings, the mechanical properties of three metal coatings of aluminum, copper, and titanium, which were deposited by warm spraying, were evaluated. The aluminum coating showed excellent ductility among them and was selected for use as ductile layers for the multilayer coatings. The fracture behavior of WC-Co/Al coatings was examined by the four-point bending test. The multilayer coatings did not break in a brittle manner after reaching maximum load, but exhibited a plateau as a result of the ductility of the aluminum layers. The fracture behavior was compared with the finite element analysis results, and they showed good agreement in a general trend. It has been concluded that ductile metal reinforcements, by advanced thermal spray techniques such as warm spray deposition, are very effective to enhance the toughness and damage tolerance of sprayed cermet coatings.     

激光重熔WC—Co涂层冲蚀性能

采用超音速火焰喷涂技术在低碳钢表面喷涂一层WC-12Co涂层,然后对其进行激光重熔处理,考察熔覆后涂层、低碳钢以及喷涂层的冲蚀磨损性能.结果表明:冲蚀角60°时熔覆层的质量损失率最大,与低碳钢和喷涂层比较,冲蚀开始阶段,熔覆层的质量损失率较低,随着冲蚀次数的增加,氧化层被冲蚀,熔覆层质量损失率升高.金相观察看出,熔覆层的致密度要优于喷涂层;硬度测试显示熔覆层硬度稍低于喷涂层.由此可推出,激光熔覆改变了涂层的组织结构,对于涂层冲蚀性能有一定影响.     

Deposition of WC-Co Coatings by a Novel High Pressure HVOF

WC-Co coatings are primarily deposited using the high velocity oxy-fuel (HVOF) spray process. However, the decomposition and decarburization of carbides during spraying affects the wear performance and fracture toughness of the coatings. In this paper, a novel high pressure HVOF was developed to achieve lower particle temperature and higher particle velocity. It enables combustion chamber pressures up to 3.0 MPa. The influence of combustion chamber pressure and oxygen/fuel ratio on WC-Co particle velocity and temperature levels were analyzed by numerical simulation. The experimental results show that the combustion chamber pressure and the oxygen/fuel ratio have a significant influence on particle velocity and melting degree, as well as on the microstructure and microhardness of the coating. High velocity WC-Co particles in different states, i.e., molten, semi-molten, and non-molten can be readily obtained by changing the spraying conditions. A comparison to the conventional JP-5000 was also performed.     

超音速等离子喷涂制备WC-12Co涂层的性能特点

超音速等离子喷涂由于喷射粒子的飞行速度(400～500m/s)相对于普通等离子喷涂(＜200m/s)有了大幅提高,所制备的WC-12Co涂层具有更高的显微硬度和结合强度.用SEM和XRD分析了两种不同等离子喷涂工艺获得的涂层的相结构和显微组织,结果表明超音速等离子喷涂WC-12Co涂层综合性能要优于普通等离子喷涂.     

Supplementary Microstructural Features Induced During Laser Surface Melting of Thermally Sprayed Inconel 625 Coatings

Laser surface melting of thermally sprayed coatings has the potential to enhance their corrosion properties by incorporating favorable microstructural changes. Besides homogenizing the as-sprayed structure, laser melting may induce certain microstructural modifications (i.e., supplementary features) in addition to those that directly improve the corrosion performance. Such features, being a direct result of the laser treatment process, are described in this paper which is part of a broader study in which high velocity oxy-fuel sprayed Inconel 625 coatings on mild-steel substrates were treated with a diode laser and the modified microstructure characterized using optical and scanning electron microscopy and x-ray diffraction. The laser treated coating features several different zones, including a region with a microstructure in which there is a continuous columnar dendritic structure through a network of retained oxide stringers.     

Microstructure Evolution of Intermetallics Produced by Laser Powder Deposition

NiAl intermetallic alloys are potential high temperaturestructural materials in aeronautical and astronauticalindustries[1].However,the poor ductility andtoughness at room temperature severely restrict theirengineering applications[2,3].It is important todevelop new technology to product intermetallicmaterials for the improvement of the comprehensiveproperties and the workability.Laser powder depositionhas been used to synthesize many new materials.Furthermore,if incorporated with rapid proto…     

铁铝混合粉热喷涂及扩散处理组织分析

利用等离子喷涂方法在不锈钢基体上喷涂铁铝混合粉获得了铁铝涂层,并对涂层的组织进行了分析。研究结果表明,Fe粉和Al粉熔化后由喷枪高速喷出,沉积在基体上可发生部分化合反应,生成少量的铁铝金属间化合物,涂层与基体结合良好。600℃扩散处理后,涂层中的铁铝金属间化合物增多。800℃和1000℃扩散处理后,Al全部反应,Fe有剩余,涂层由Fe、铁铝金属间化合物和氧化物组成。