Cold Spray Deposition of Ni and WC-Reinforced Ni Matrix Composite Coatings

Ni-WC composites are ideal protective coatings against wear and are often fabricated using laser cladding and thermal spray processes, but the high temperatures of these processes result in decarburization, which deteriorates the performance of the coating. Cold spray has the potential to deposit Ni-WC composite coatings and retain the composition of the initial WC feedstock. However, the insignificant plastic deformation of hard WC particles makes it difficult to build up a high WC content coating by cold spray. By using three different WC powder sizes, the effect of feedstock powder size on WC retention was tested. To improve WC retention, a WC/Ni composite powder in mixture with Ni was also sprayed. Microstructural characterization, including the deformed structure of Ni splats, retention, distribution, and fragmentation of WC, was performed by scanning electron microscopy. An improvement in WC retention was achieved using finer WC particles. Significant improvement in WC particles retention was achieved using WC/Ni composite powder, with the WC content in the coating being close to that of the feedstock.     

Plasma Spray Deposition and Engineering Applications of Magnesium Hydroxide-polyamide Composite Coatings

Magnesium hydroxide is shown to dehydrate endothermically to magnesium oxide over a similar temperature range to that of the thermal degradation of polyamide. The extent of dehydration in plasma spraying is shown to be a function of particle size. However the research indicates that the use of magnesium hydroxide as a filler in plasma sprayed polyamide composite coatings does not significantly increase the quality of the matrix by suppressing its degradation. A high content of unreacted magnesium hydroxide can be obtained in plasma sprayed polyamide composites by control of the feedstock particle size. The practical implications of the results for potential engineering applications of the composite are discussed in terms of wear resistance and fire retardance.     

Plasma Spray Coatings of Ni-Al-SiC Composite

Ni-Al-SiC powder mixture containing 12 wt.% SiC was prepared by conventional ball milling. Morphological and microstructural investigations showed that powder particles after 15 h of milling time had the optimum characteristics with respect to their size and microstructure. X-ray diffraction patterns of powder particles included only the elemental Ni, Al, and SiC peaks without any traces of oxides or intermetallic phases. The powder mixture was then deposited onto a steel substrate by atmospheric plasma spray (APS) process under different conditions. The results showed that under APS conditions used here, the coatings were composed of various intermetallics including Ni-Al and Ni₂Al₃. The mean hardness of coating was found to be about 567 HV. It was also found that by increasing current density of APS, the coating/substrate adhesive strength was increased.     

脉冲电化学沉积法制备钛基HA/Ag复合涂层

采用脉冲电化学法在生物医用钛表面制备出纳米HA/Ag复合涂层。借助SEM、XRD等对复合涂层的形貌、成分进行表征。利用大肠杆菌和白色葡萄球菌两个菌种对该涂层抗菌性能进行分析研究。最后利用MC3T3-E1成骨细胞检测复合涂层的细胞相容性。结果表明：HA/Ag复合涂层呈纳米球状,由HA和Ag两相组成。Ag在HA涂层中分布均匀。复合涂层对两种细菌均有较好的抗菌效果,对大肠杆菌抗菌率达100%,对白色葡萄球菌的抗菌率接近100%,对大肠杆菌的抗菌能力高于白色葡萄球菌。细胞培养实验表明MC3T3-E1成骨细胞在HA/Ag复合涂层表面的黏附、铺展较好。综合可知,脉冲电化学沉积法制备的纳米HA/Ag复合涂层具有较好的抗菌性和细胞相容性     

以沥青为前驱体制备TiC/FeCrNi反应火焰喷涂复合涂层

以钛铁粉、CrFe粉、羰基镍粉和碳的前驱体（石油沥青）为原料,通过前驱体碳化复合技术制备了Ti-Fe-Cr-Ni-C反应喷涂复合粉末,并通过普通火焰喷涂成功地合成与沉积了TiC/FeCrNi复合涂层.采用XRD和SEM对喷涂粉末和涂层的相组成和显微结构进行了分析,同时对涂层耐磨性能进行了对比研究.研究结果表明：采用前驱体碳化复合技术制备的Ti-Fe-Cr-Ni-C反应喷涂复合粉末粒度均匀、无有害相生成;所制备的TiC/FeCrNi复合涂层由不同含量TiC颗粒分布于金属基体内部而形成的复合强化片层叠加而成,TiC颗粒呈纳米级;基体由（Fe,Cr）和Cr0.19Fe0.7Ni0.11两相组成;相同条件下,所获TiC/FeCrNi复合涂层磨损体积大约是常规火焰喷涂Ni60涂层的1/8.     

氧乙炔火焰喷焊镍基复合涂层的显微组织和腐蚀性能研究

目的 研究Ni60和Ni60WC喷焊涂层的显微组织、防腐和耐磨性能及其腐蚀机理,为恶劣工况下服役的零件选择合适的喷焊涂层提供参考.方法 采用氧乙炔火焰喷焊工艺在16Mn钢基体上制备Ni60和Ni60WC涂层,用X射线衍射仪、金相显微镜和扫描电子显微镜分析了喷焊涂层的相结构和显微组织,并采用电化学工作站、盐雾腐蚀试验机、...     

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.     

Ti基板上磷酸钙薄膜的电沉积

主要研究电沉积条件如何影响沉积产物磷酸钙涂层的晶相。实验采用金属Ti作为基板,电解液为Ca(NO3)2(45mmol/L)与NH4H2PO4(25mmol/L)的稀混合液,通过改变沉积温度、沉积时间、电解液的pH值等参数,利用XRD、SEM表征沉积产物。结果显示:温度对晶相转变的影响最大,37℃时获得的晶相只有DCPD(CaHPO4·2H2O),当沉积温度升高到60℃时,HAP(Ca10(PO4)(OH)2)相含量增加。沉积时间对沉积产物的晶相类型没有影响。随着pH值的升高,DCPD和OCP(Ca8(HPO4)2(PO4)4·5H2O)相含量均在增加,证明高pH值不仅能影响晶相生长,而且能诱导晶相转变。SEM结果表明,在3V的沉积电压下,都能够得到厚度均匀的沉积涂层,但是以45℃为沉积温度并沉积15min时,Ti基板上得到的磷酸钙盐涂层最均匀,并且得到的HA前躯体比较有利于实验后处理,以得到质量较好的HA涂层。     

火焰喷涂玻璃涂层的耐蚀性研究

研究了手工火焰喷涂玻璃涂层的腐蚀破坏机理。试验结果表明：在涂层冷却凝固过程中，由于残余应力的作用，形成了缺陷。在腐蚀过程的初期阶段，缺陷处形成腐蚀斑点。随着腐蚀过程的进行，腐蚀斑点逐渐扩大，最终导致整个涂层破坏。涂层破坏的主要原因是和腐蚀介质接触的底釉层首先被腐蚀掉，然后面釉层在残余应力的作用下断裂、塌陷，被分解为小碎片。该腐蚀特点是由玻璃涂层的结构、脆性和制备工艺决定的。可以通过优化喷涂工艺来改善涂层的耐蚀性。     

Cold Spray Deposition of Copper Electrodes on Silicon and Glass Substrates

Copper lines with widths varying from 150 to 1500 μm were deposited onto crystalline silicon wafers and soda-lime glass plates by cold spraying copper particles with 1 μm average diameter through a mask. This direct deposition method yielded high-aspect-ratio electrodes with minimum shadowing effects and maximum electrode-to-silicon contact area. The copper lines had triangular cross sections with aspect ratios (height/width) ranging from 0.1 to 1.1, depending on the number of spray gun passes. Copper particles were densely packed with increasing the width of the masking slit. This study presents the potential use of the cold spray technology in printing lines as front electrodes in solar cell applications.     

Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review

Titanium dioxide has been the most investigated metal oxide due to its outstanding performance in a wide range of applications, chemical stability and low cost. Coating processes that can produce surfaces based on this material have been deeply studied. Nevertheless, the necessity of coating large areas by means of rapid manufacturing processes renders laboratory-scale techniques unsuitable, leading to a noteworthy interest from the thermal spray (TS) community in the development of significant intellectual property and a large number of scientific publications. This review unravels the relationship between titanium dioxide and TS technologies with the aim of providing detailed information related to the most significant achievements, lack of knowhow, and performance of TS TiO₂ functional coatings in photocatalytic, biomedical, and other applications. The influence of thermally activated techniques such as atmospheric plasma spray and high-velocity oxygen fuel spray on TiO₂ feedstock based on powders and suspensions is revised; the influence of spraying parameters on the microstructural and compositional changes and the final active behavior of the coating have been analyzed. Recent findings on titanium dioxide coatings deposited by cold gas spray and the capacity of this technology to prevent loss of the nanostructured anatase metastable phase are also reviewed.     

Effect of Ceramic Particle Velocity on Cold Spray Deposition of Metal-Ceramic Coatings

In this paper, metal-ceramic coatings are cold sprayed taking into account the spray parameters of both metal and ceramic particles. The effect of the ceramic particle velocity on the process of metal-ceramic coating formation and the coating properties is analyzed. Copper and aluminum powders are used as metal components. Two fractions of aluminum oxide and silicon carbide are sprayed in the tests. The ceramic particle velocity is varied by the particle injection into different zones of the gas flow: the subsonic and supersonic parts of the nozzle and the free jet after the nozzle exit. The experiments demonstrated the importance of the ceramic particle velocity for the stability of the process: Ceramic particles accelerated to a high enough velocity penetrate into the coating, while low-velocity ceramic particles rebound from its surface.     

Deposition Behavior of Semi-Molten Spray Particles During Flame Spraying of Porous Metal Alloy

Porous 316L stainless steel deposits were fabricated by flame spraying semi-molten particles with different melting degrees and spray angles to understand the deposition behavior of semi-molten spray particles. The effects of spray angle relative on the deposition efficiency and deposit porosity were investigated. The morphology of individual splats deposited on flat surface at different angles was examined. The results show that the spray angle had a significant influence on the deposit porosity, pore structure, and deposition efficiency. The slipping of solid core in semi-molten spray particle was clearly observed when semi-molten particles impacted on the polished substrate with an inclined angle. A random model was proposed to simulate the process of particle deposition. It was found that after considering the effects of both solid particle slipping upon impact and particle melting degree, the porosity calculated by simulation with the model agreed well with the experimental observation.     

On the Electrochemical Deposition and Properties of Nickel-Based Composite Coatings

Protection of Metals and Physical Chemistry of Surfaces - Nickel-based composite electrochemical coatings (CECs) modified with graphite nitrate have been obtained. Their microstructure and...     

电泳-电沉积法制备超疏水Ni-PTFE复合镀层

通过电泳-电沉积法制备具有超疏水特性的金属基镍(Ni)-聚四氟乙烯(PTFE)复合镀层。在改善搅拌方式和优选表面活性剂添加量的基础上,重点分析了电流密度和镀液中PTFE微粒子含量对镀层润湿性的影响。结果表明:在镀液中的PTFE微粒子含量90 g/L、且每克PTFE(平均粒径0.2μm)辅助有65 mg的FC-134表面活性剂的条件下,能制备出具有超疏水与疏油特性的Ni-PTFE复合镀层。     

喷射沉积SiCp/6066铝基复合材料的固溶温度

研究了射沉积体积分类１０％、ＳｉＣｐ／６０６６铝基复合材料的固溶温度。结果表明,Ｍｇ和Ｃｕ在界面的富集致使使复合材料的固溶温度和过烧温度均低于基体结合。该复合材料的最佳固溶温度５１５℃,且在５４０℃过烧。     

低压冷喷涂镍基金属陶瓷复合涂层的摩擦学性能研究

目的 研究镍基陶瓷复合涂层的摩擦学性能,为现场修复泥浆泵关键部件提供实验支撑.方法 采用低压冷喷涂技术,在Q235钢表面分别制备不同Al2O3和ZrO2含量的镍基金属陶瓷复合涂层.通过HT-1000摩擦实验机测试大气气氛下涂层的摩擦磨损性能,采用X射线衍射仪(XRD)和附带能谱的扫描电镜(SEM)表征复合涂层的微观组织...     

火焰喷涂EAA/n-SiO2复合涂层热力学性能

采用火焰喷涂的方法制备了EAA(乙烯-丙烯酸共聚物)及其纳米SiO2(n-SiO2)复合涂层,利用电子拉力机、傅立叶红外光谱仪(FTIR),差示扫描量热仪(DSC)、热重分析仪(TG)对涂层的力学性能、热性能等进行了测试分析.结果表明:在适当的喷涂工艺条件下,物料在火焰喷涂过程中没有发生氧化或降解;DSC、TG分析表明n-SiO2具有明显的成核剂作用,n-SiO2的加入提高了复合涂层的结晶度,加速复合涂层的结晶速度;在n-SiO2含量为2.0%时,复合涂层表现出较好的综合性能,涂层与基体的结合强度达到26.30MPa,涂层自拉伸强度为33.87MPa,较纯涂层提高了30.6%.     

冷喷涂TC4涂层临界沉积速度计算及制备涂层性能研究

目的研究冷喷涂TC4涂层的临界沉积速度及粒子温度对临界沉积速度的影响规律,并研究气体压强对沉积涂层性能的影响规律。方法理论研究上,采用有限元LS-DYNA软件中的Johnson-Cook塑性模型,选取3D164计算单元建立模型,研究粒子在不同温度和不同速度下碰撞基体后的形貌特征,确定粒子沉积临界速度。试验研究上,采用N_2作为冷喷涂驱动气体,在TC4合金上制备TC4涂层,然后采用SEM、Image J图像分析软件、硬度计等分析已沉积涂层的孔隙率和硬度等性能。结果 25、400、500、600℃温度下,计算表明10μm的TC4合金粒子在TC4基板上的临界沉积速度分别为730、465、392、361 m/s,即随粒子温度升高,粒子临界沉积速度降低,粒子沉积成涂层更容易。采用冷喷涂工艺在TC4基板上沉积TC4涂层,在N_2温度600℃、气体压力3 MPa的条件下,制备的TC4涂层厚度约1000μm,与TC4钛合金基体结合紧密,涂层孔隙率约为6.46%。结论气体温度升高,粒子临界沉积速度降低;气体压强变大,制备的涂层厚度就大且更加致密。