Corrosion Performance of Zinc and Zinc-cobalt Alloy Compositionally Modulated Multilayer （CMM） Coatings

Varieties of zinc and Zn-Co alloy compositionally modulated multilayer （CMM） coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated samples were examined using scanning electron microscopy （ SEM ）. The existence of iuternal stress in ZnCo alloy deposits was confirmed by the cross-sectional morphalogies for the occurrence of micro-cracks in the thick Zn-Co alloy deposit alone. The corrosion performance was evaluated using neutral salt spray testing, corrosion potential measurement and anodic polarization methods. The experimental results slum, that the zinc and Zn- Co alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Co alloy alone with a similar thickness. The analysis on the micrographic features of zinc and Zn-Co alloy CMM coatings, using field emission gun scanning electron microscopy （FEGSEM） after corrosion testing, explains the probable reusons why the Zn-Co/ Zn CMM coating system has a better protective performance.     

Corrosion protection of AM50 magnesium alloy by Nafion/DMSO organic coatings

The effectiveness of the corrosion protection of Nafion/Dimethysulfoxid （DMSO） organic coatings for AM50 magnesium alloy prepared by simple immersion and heat treatment was investigated. Its corrosion resistance and morphologies of the Nafion/DMSO organic coatings were studied by electrochemical corrosion testing and optical microscopy. The results show that Nafion/DMSO organic coatings can improve the corrosion resistance of AM50 magnesium alloy effectively. Also, the corrosion resistance increases with the surface density of the organic coatings.     

电弧离子镀TiN/TiAlN复合涂层摩擦磨损性能研究

利用阴极电弧离子镀技术,在硬质合金基体上制得5层和20层TiN/TiAlN复合涂层.研究表明,这两种涂层均为典型的B1-NaCl面心立方结构,且均呈(200)择优取向.两种涂层表面光滑平整,粗糙度分别为0.32和0.11,硬度为1 470HV和2 000HV .20层复合涂层的摩擦系数和比磨损率低于5层,表明增加复合层数有利于提高涂层的耐磨损性能,涂层的磨损机理为磨粒磨损.     

铝合金上电沉积Ni-P-CNTs复合镀层及其摩擦性能研究

采用复合电沉积法在铝合金表面上制备了镍 磷 碳纳米管（Ni-P-CNTs）复合镀层,并用X射线衍射（XRD）和扫描电镜（SEM）对其进行了表征,分析了电流密度和镀液中碳纳米管的质量浓度对复合镀层形貌及其摩擦磨损性能的影响.当电流密度为3.0 A/dm2时可以得到表面光亮、平整的复合镀层,复合镀层中碳纳米管体积分数随着镀液中碳纳米管质量浓度的增加而增加.Ni-P-CNTs复合镀层比Ni-P镀层具有更高的硬度、耐磨性能和更低的摩擦系数.随着复合镀层中碳纳米管体积分数的增加,复合镀层的磨损量和摩擦系数逐渐降低.复合镀层摩擦性能的改善是由于碳纳米管具有优异的力学性能和良好的自润滑性能.     

锌镍合金电镀液在线分析中分离技术的研究

研究了锌镍合金电镀液在线分析中的萃取色层分离技术，通过对两种方法（负载法与合成法）制备的萃淋树脂的性能研究及萃取色层柱分离条件的考察，建立了以１－（２－吡啶偶氮）－间苯二酚为显色剂，在线分析的萃取色层分离光度分析方法，利用此法可将锌镍完全分离，实现锌镍的同时检测。该法的准确度和精密度均令人满意，变异系数小于１．２％，两种萃淋树脂的吸附容量分别可达１．９１ｍｇ／ｇ和８．７０ｍｇ／ｇ干树脂。     

Composition and Morphology of Zn-Co Alloy Coatings Deposited by Means of Pulse Plating Containing Reverse Current

The influence of bath constituents and pulse parameters on cobalt content, surface morphologies and grain size of Zn-Co alloy deposits was studied using a pulse plating technique with a square- wave current containing reverse pulse, It is found that Zn-Co alloy coatings obtained from the bath with the cobalt ion concentration over 60 wt% have a higher cobalt content in deposits. The results of pulse plating show that the average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. It is possible to electrodeposit Zn-Co alloy coatings with 10-90 wt% cobalt by modulating pulse parameters. The grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current.     

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO_2 composite electrodeposition

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO2 composite electrodeposition in alkaline zincate solutions were studied respectively by the methods of linear potential sweep and cyclic voltammetry. From the results it can be concluded that Zn shows under potential deposition, Zn-Fe alloy codeposition is anomalous codeposi-tion and Zn-Fe alloy cathode polarization is increased with the introduction of additive. From the view point of electrochemistry, the reasons that the content of Fe in the Zn-Fe coating changes with the composition of the electrolyte and the process conditions altering and the relationship between the content of Fe and the appearance of the coating are interpreted. The cathode polarization of Zn-Fe alloy codeposition is enhanced obviously with addition of additive. In the course of composite electrodeposition, TiO2 has less promotion to electrodeposition of zinc ions than to iron i-ons, while the electrodeposition of iron ions improves the content of TiO2 in composite coating,     

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO2 composite electrodeposition

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO₂ composite electrodeposition in alkaline zincate solutions were studied respectively by the methods of linear potential sweep and cyclic voltammetry. From the results it can be concluded that Zn shows under potential deposition, Zn-Fe alloy codeposition is anomalous codeposition and Zn-Fe alloy cathode polarization is increased with the introduction of additive. From the view point of electrochemistry, the reasons that the content of Fe in the Zn-Fe coating changes with the composition of the electrolyte and the process conditions altering and the relationship between the content of Fe and the appearance of the coating are interpreted. The cathode polarization of Zn-Fe alloy codeposition is enhanced obviously with addition of additive. In the course of composite electrodeposition, TiO₂ has less promotion to electrodeposition of zinc ions than to iron ions, while the electrodeposition of iron ions improves the content of TiO₂ in composite coating, which is in agreement with the results of process experiments.     

Application of a novel multilayer spray forming technology in the preparation of large dimension aluminium alloy blanks

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激光熔覆铜基合金涂层中的液相分离行为

为了研究铜基合金激光熔覆中的液相分离行为,根据液相分离理论在ZL104铝合金表面成功制备了具有液相分离特性的铜基合金涂层,并采用扫描电镜等对涂层中液相分离形成的分离相(硬质强化相)的形态特征与分布规律进行了观察,研究了不同分离相的形成机制与液相分离行为.研究表明,涂层中的分离相通常呈弥散分布和偏聚2种典型形态.熔池温度较高时分离相表现出"富Mo核心 包围相"的2层复合结构,呈边缘粗糙的不规则近球状形貌,这是由异质形核诱发的液相分离所形成的;温度稍低时强的表面能约束则是影响液相分离的主要因素,并使分离相呈光滑球状形态.当表面能过高时在对流等因素作用下分离相问会发生严重的碰撞凝并,最终形成大块偏聚体.     

Electrodeposition of Ni-Co-Fe2O3 composite coatings

Ni-Co-Fe₂O₃ composite coatings were electrodeposited using cetyltrimethylammonium bromide (CTAB)-modified Watt’s nickel bath with Fe₂O₃ particles dispersed in it. The effects of the plating parameters on the chemical composition, structural and morphological characteristics of the electrodeposited Ni-Co-Fe₂O₃ composite coatings were investigated by energy dispersive X-ray (EDS) spectroscopy, X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results reveal that Fe₂O₃ particles can be codeposited in the Ni-Co matrix. The codeposition of Fe₂O₃ particles with Ni-Co is favoured at high Fe₂O₃ particle concentration and medium stirring, and the deposition of Co is favoured at high concentration of CTAB. Moreover, the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed 〈220〉 preferred orientation. Composites with high concentration of embedded particles exhibit a preferred crystal orientation of 〈111〉. The more the embedded Fe₂O₃ particles in the metallic matrix, the smaller the sizes of the crystallite for the composite deposits.     

Composition and hardness of mullite coatings formed with direct current power supply on LY12 aluminum alloy surface

The surface modification of aluminum and its alloys using plasma technology is increasingly being investigated, Thick ceramic coatings with high hardness on aluminum alloys can be prepared successfully using a micro-plasma oxidation （MPO） technique. In this work, the composition, microstructure and elemental distribution of ceramic coatings formed by MPO on LY 12 almnlnum alloy and its hardness are investigated using XRD, EPMA and microhardness instruments. The results show that the ceramic coatings consist of mullite,γ-Al2O3 and a lot of amorphous matter. The content of silicon in the coatings increases from interface to the coatings, however, the content of aluminum decreases along this direction. The maximum hardness of ceramic coatings is up to 9.2 GPa.     

结构调制高硬度TiCu/TiN-Cu纳米多层复合膜制备及其机械性能

为改善TiN硬质薄膜的硬度和耐摩擦磨损性能,采用多弧离子镀技术,在硬质合金基底上制备了单层TiN-Cu薄膜和调制周期Λ=5.9～62.1 nm的5组TiCu/TiN-Cu纳米多层复合膜.使用扫描电子显微镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)、纳米压痕仪、划痕仪和摩擦磨损试验机等测试仪器,表征了薄膜...     

Electrodeposition of Ni-Cr alloy on aluminum substrate

1 INTRODUCTIONOwing to low mass , high strength and easymachining, aluminum ( Al) and its alloys havebeen widely appliedin many fields .But the chemi-cal character of Al is very active ,it can be oxidizedeasilyinthe at mosphere and erodedinthe foul con-dition,and its wear resistance is poor . All theseseriously affect its application andlifeti me .It is aneffective protective measure to i mprove perform-ance by means of plating alloy on Al substrate .Ni-Cr alloys have many characteristi…     

Ni-Cr alloy electrodepositing technology on Fe substrate and coating performance

The Ni-Cr alloy electrodepositing technology on iron substrate in the chlorid-sulfate solution and the impacts of main processing parameters on coating composition were studied. The optimal Ni-Cr alloy electrodepositing conditions are that the cathode current density is 16 A/dm^2, the plating solution temperature is 30 ℃ and the pH value is 2.5. The bright, compact coating gained under the optimal conditions has good cohesion and 24.1% Cr content. The results show that the coating is composed of crystalline, the average grain size is 82 nm and the higher the Cr content of coating, the larger the rigidity, and the higher the corrosion resistance. The rigidity of coating reaches 78.6（HR30T） and the passivation area broadens to 1.4 V when the Cr content of coating is 24.1%.     

磷化液的pH值对AZ61镁合金锌系磷化膜的影响

探讨了AZ61镁合金在不同pH值的磷化液中制得的磷化膜的性能和表面形貌。通过腐蚀失重试验、阳极极化曲线测试和交流阻抗测试对磷化膜的耐蚀性进行了研究,利用金相显微镜、热场发射扫描电镜分析了磷化膜的外观结构。实验结果表明:磷化液的pH值对磷化膜的耐蚀性和表面形貌有很大影响。在低pH值的磷化液中得到的磷化膜疏松多孔、耐蚀性差;在高pH值的磷化液中得到的磷化膜外观粗糙、耐蚀性差;在磷化液pH值适中(pH值为2.5)的磷化液中所得的磷化膜外观细致均匀、耐蚀性好。     

镁合金表面的腐蚀特性及其防护技术

从镁合金表面自然氧化的微观结构与形成过程入手,论述了其表面多孔 状的三层氧化膜造成镁合金基体表面容易发生腐蚀的原因,并详述镁合金表面的电化学腐蚀特性与腐蚀机理;从三个不同角度分析其独特的负差数效应,并用“部分膜保护机制”对此作出更合理的解释;讨论了阳极氧化技术及其在此基础上之上发展而来的等离子微弧阳极氧化技术,该技术可显示提高镁合金表面氧化膜的耐蚀性与抗磨性。介绍了包括激光表面热处理和激光合金化的激光辅助处理技术,它能对镁合金表面进行快速、局部的处理,提高材料的耐腐蚀性能和硬度,概述了物理气相沉积技术,它可为镁合金表面提供耐腐蚀性能、高结晶度和高强度。讨论了目前国内外最新研究的用于取代有毒的铬酸盐转化膜的稀土转化膜工艺的化学法;该方法具有操作简便、无毒无污染等诸多特点,可以明显提高镁合金表面的耐腐蚀性能,但机理研究有待于进一步探讨。     

锂离子电池中电沉积锡镍合金电极的嵌锂性能

为获得具有更高比容量的锂离子电池负极材料,通过电沉积方法制备了Sn—Ni合金电极．对合金镀层组成与形貌进行了表征,测试了电极的电化学性能．电沉积Sn—Ni合金电极是Ni,Sn2和Sn复合电极,电极中Sn与Ni的摩尔比为1：1．15,电极首次放电容量可达500mAh／g,库仑效率88％,前10次循环库仑效率都在98％以上,50次循环时放电容量仍可达350mAh／g,库仑效率在94％以上．循环伏安和微分容量曲线都表明,多次循环后的电极完全表现出电沉积Sn电极的特征．扫描电镜照片表明,循环后的Sn—Ni合金电极发生了严重的膨胀和破裂．     

Hydrogen-induced cracking behaviors of Incoloy alloy 825

The effect of hydrogen on the fracture behaviors of Incoloy alloy 825 was investigated by means of slow strain rate testing (SSRT).Hydrogen was introduced into the sample by electrochemical charging.The results show that surface microcracks form gradually during aging at room temperature when desorption of hydrogen takes place after hydrogen charging at a current density of 5 mA/cm 2 for 24 h.SSRT shows that the increase of ductility loss is significantly obvious as the hydrogen charging current density inc...