硫酸盐酸性光亮镀锡铋合金工艺

采用赫尔槽试验研究了硫酸盐酸性电镀锡铋合金工艺。以改善镀层的光亮性以及镀液的稳定性为目的,讨论了镀液组分及工艺条件对镀液和合金镀层性能的影响,检测了镀液和镀层的相关性能。结果表明:镀液中加入光亮剂和稳定剂后,可获得一种铋含量达2.5%,且耐蚀性、可焊性优良的光亮Sn-Bi合金镀层。镀液的覆盖能力和分散能力良好,镀液稳定性也得到较大提高。     

环保型镀锡液性能研究

环保型镀锡液是一种环保性好、生产效率高、性能优良的新型镀锡液.采用赫尔槽试验、电化学测试等手段,对镀液的电导率、沉积速率、分散能力、覆盖能力、镀液的极化能力以及镀层性能分析研究,结果表明:该镀液在45℃时的电导率为176mS/cm,镀液的分散能力和履盖能力分别为97.8%、82.4%,镀液的极化能力强,得到的镀层结晶细致,添加剂加入后明显改善了镀液的极化性能,提高了锡离子的析出电位.     

铈盐对电镀锡参数和性能的影响

研究了镀液中铈盐含量不同时对电镀锡参数及性能的影响.测定了镀液的均镀能力和镀层抗介质腐蚀的能力,探讨了铈盐的加入对镀层电导率的影响,实验证明,一定量铈盐的加入可扩大阴极电流密度范围,增强镀液的均镀能力,加宽镀层的光亮范围,提高镀层的耐蚀性和镀层的电导率,结果表明,铈盐的最佳添加量为15g/L.     

超声电镀锡铋合金研究

研究了超声波对锡铋合金电镀的影响.通过赫尔槽试验优选出最佳镀液配方和工艺条件,用SEM法观测了镀层形貌,并测试了镀层和镀液性能.结果表明:超声波的作用扩大了电流密度范围和温度范围;所得镀层表面光亮、结晶更细致、均匀,镀层结合力、抗氧化性和可焊性改善明显,耐蚀性增强;镀液性能稳定,阴极电流效率和沉积速度得到提高.因此,超声波对电镀工艺条件、镀层质量和镀液性能都有明显的改善作用.     

Ni-B合金电沉积工艺性能研究

研究了Ni-B合金电沉积的镀液、镀层性能.阴极极化曲线实验结果表明Ni-B合金电沉积是典型的诱导共沉积类型.镀液稳定性高,镀层硬度高,镀态硬度值可达700～800HV,耐磨性好.镀层具有一定的耐酸能力和很强的耐碱液腐蚀能力.     

高分散光亮酸性镀铜新工艺

采用霍尔槽法及电化学法研究了添加剂对镀层质量、镀液分散能力的影响.结果表明随着添加剂BSP,H1,PN,PEG加入量增大,镀层光亮区和镀液分散能力均先增大后减小.X型光亮剂酸性镀铜新工艺适宜条件下可在20～40℃下得到光亮平整的镀层,对应电流密度0.5～14.3 A/dm2.施镀15 min,镀液分散能力可达32.8%...     

稀土对电沉积Zn-Fe-La三元合金性能影响的研究

为了获得更加光亮、致密的Zn-Fe-La三元合金镀层,针对电沉积Zn-Fe-La三元合金镀液组成及工艺条件,系统地研究了稀土对镀层成分含量、镀液稳定性、镀液分散能力以及pH值的影响,测定了镀层的极化曲线、稳定电位和极化电阻,比较了不同稀土含量对镀层耐蚀性的影响.结果表明:稀土的加入可提高镀液稳定性、分散能力,增加电沉积过程阴极极化,使阳极钝化前的活性区腐蚀电位正移,自溶解速度下降,有利于提高镀层耐蚀性,其耐蚀性比Zn-Fe合金镀层及纯Zn镀层有很大提高.     

稳定剂对96Al2O3陶瓷表面化学镀铜的影响

为改善甲醛、酒石酸钾钠体系的镀液稳定性,实验研究了分别添加及同时添加甲醇、亚铁氰化钾两种稳定剂,对96Al2O3陶瓷基片化学镀铜的沉积速度、外观及镀液稳定性的影响.结果证明,单一加入甲醇能很好改善镀液稳定性,适量的甲醇还能提高沉积速度;单一加入亚铁氰化钾也能明显改善镀液稳定性,而且还能改善镀层外观质量,但沉积速度下降;同时添加两稳定剂,可在沉积速度不降低的前提下,明显改善了镀液稳定性和镀层外观质量.     

镀镍液中氯化镍的作用和分析方法的改进

1氯化镍的作用 镀镍溶液中的氯化镍作为阳极活化剂,能提高镀液的导电性能.其含量过低时镍阳极容易钝化,镀液中硫酸镍的含量降低,影响溶液的稳定;含量较高虽然可以提高溶液的导电性能和分散能力,但阳极溶解异常快,泥渣增多,进而使镍镀层产生毛刺、粗糙,镀层内应力增加,也是镀层产生脆裂的潜在因素;对于镀珍珠镍而言,镀液的分散能力不能太高,要求氯化镍含量低一些;对于深孔镀镍和滚镀镍而言,氯化镍含量应高一些,以提高镀液的深镀能力和分散能力.     

多孔不锈钢网状材料表面光亮镀镍工艺的研究

采用三相桥式可控整流电路电源和自制的简易镀液槽,通过电镀的方法在316L不锈钢多孔金属烧结网状材料表面覆盖一层光亮金属镍层,研究镀液和镀层的性能。结果表明,该镀镍工艺配方光亮范围宽,镀液性能稳定,整平能力、分散能力和覆盖能力较好,镀液温度、电流密度和p H值易控制,可以获得外观光泽明亮,镀层结合牢固的镀层。     

Effect of joining temperature on the microstructure and strength of tungsten/ferritic steel joints diffusion bonded with a nickel interlayer

A diffusion bonding process, for joining of tungsten to ferritic steel using nickel as an interlayer, was developed for nuclear component application. The effect of joining temperature on the microstructure and tensile strength of the joint was investigated in this work. Metallographic analysis revealed that a good bonding was obtained at both the tungsten/nickel and nickel/steel interfaces, and the diffusion products were identified in the diffusion zone. Nano-indentation test across the joining interfaces demonstrated the effect of solid solution hardening in the diffusion zone. Tensile test showed that the maximum average tensile strength of ∼200 MPa was obtained for the joint diffusion bonded at 900 °C. The results were discussed in terms of the joining temperature and of the residual stress generated during joining process.     

Rapid Hydrogen Transportation Along Grain Boundary in Nickel

The permeability and diffusivity of hydrogen in directionally solidified polycrystalline and single crystal nickel foils were measured by gas permeation method.The results showed that both hydrogen diffusivity and permeability were higher in directionally solidified nickel specimen than those in single crystal one at the temperature ranging from 300 to480 °C,and confirmed the existence of short-circuit diffusion along the grain boundaries(GBs) in the directionally solidified nickel.The results suggested that the rapid diffusion along GBs was more obviously characterized in terms of higher permeability rather than higher diffusivity.The contribution of grain boundary to hydrogen transportation was represented by the differences of diffusivity(and permeability) in single crystal nickel and directionally solidified nickel.By modifying the Fick's first diffusion law and counting the grain boundary density,the hydrogen diffusivity and permeability of rapid diffusion along GBs were calculated.The results suggested both the diffusivity and permeability fit the Arrhenius relationship well at different temperature.     

Influence of external mechanical loadings (creep,fatigue) on oxygen diffusion during nickel oxidation

This study deals with the influence of various mechanical loadings (fatigue, creep, creep-fatigue) on oxygen diffusion in a particular system, oxidizing nickel. A distinction between the behavior of the oxide layer and underlying nickel was noted during the first step of oxidation at 550°C, in P_{O 2}=1 atm. Mechanical loading causes a decrease of the oxygen mobility through the oxide scale (factor of 10³). The oxide thicknesses on nickel undergoing mechanical loadings are different than for an unloaded sample, due to distinct contributions of the oxygen and nickel fluxes in the growing oxide. In the substrate, the ingress of oxygen becomes easier with a constant tensile load (creep). The intergranular-oxygen diffusion coefficient, D_i, is increased by a factor of 10² with respect to other samples. In creep, oxygen diffusion takes place along grain boundaries of a structure with smaller grains than in unstrained Ni. A short fatigue period during creep-fatigue decreases the sensitivity of nickel to intergranular-oxygen diffusion.     

Short-circuit diffusion in the growth of nickel oxide scales on nickel crystal faces

A study has been made of the growth of nickel oxide layers on the (100), (110), and (111) crystal faces of nickel exposed to oxygen for periods up to 100 hr at temperatures in the range 500–800°C, These layers grow at a rate dependent upon the crystallographic orientation of the nickel face even at thicknesses within the scaling range. The (100) face oxidized more rapidly than the (110) and (111) nickel faces while the latter faces oxidized at different relative rates dependent upon temperature. A diffusional model is employed to interpret the oxidation kinetics wherein nickel transport proceeds in nickel oxide both by short-circuit diffusion at grain boundaries and by lattice diffusion.This work forms part of a research program sponsored by the National Research Council of Canada.     

The Effect of Surface-Layer Modification of Nickel Alloys on the Heat Resistance of Aluminide Coatings Applied on Gas-Turbine Blades

A method for the preparation of a complex diffusion coating by preliminary saturation of the surface layer of heat-resistant nickel alloys with nickel and by subsequent chrome aluminizing in vacuum using powder mixtures at processing temperatures of 1000 and 1200°C is analyzed. The characteristics of the chemical composition and structure of coatings and comparative data on the heat resistance at temperatures of 1000, 1050, and 1100°C under the conditions of isothermal oxidation are given. It is shown that the complex coating exhibits increased heat resistance owing to an increase in the uniformity of the surface alloy layers obtained by the diffusion nickel plating.     

Impact of the nickel interlayer on the electrical resistance of tin-tin interface submitted to fretting loading

The behaviour of the tin/tin interface for electrical contact application is addressed in this paper. Two coating systems were studied: a bronze-tin coating system and a bronze-nickel-tin coating system. The transition amplitude δ_t from partial slip (P.S) to gross slip (G.S), defining the domains of infinite and finite lifetime of the contact, was found using the variable-displacement-amplitude methodology (VDA). Constant-displacement-amplitude (CDA) tests were performed in order to determine the influence of the nickel interlayer on the performance of the electrical contact. The conducted analysis concluded that there is no influence of the nickel interlayer on the electrical endurance during G.S. However, the nickel interlayer, which serves as a diffusion barrier, eliminates the diffusion of copper through the tin coating; thus preventing the formation of copper oxides on the top surface. It concludes that the application of the nickel underlayer by maintaining high tin-tin friction coefficient extends the P.S domain and therefore increases the reliability of the electrical contact.     

铈离子对镍电结晶过程的影响

为了解铈离子对镍电沉积电极过程的影响,采用线性扫描伏安法、单电位阶跃计时电流法、交流阻抗谱等方法,对镍在玻碳电极上的电沉积进行了研究。实验结果表明：CeCl3的加入使镍离子的扩散系数下降、电荷传递电阻增大,加大了镍沉积的阴极极化,同时使电结晶成核速率常数增大,晶体向外生长速度下降。这些变化可能与Ce^3＋及在沉积过程中形成的Ce^3＋多核配离子吸附在阴极表面有关。但铈离子的加入没有改变镍在玻碳电极上的电结晶成核机理。     

Alloying of Stacked Tin and Nickel Surface Films on Iron Substrate and Its Limitation

Stacked single layers of tin and nickel usually made by electrodeposition were prepared by a sputtering process in this study and the alloying behaviour through heating in an electric furnace was investigated by SEM-EDX and X-ray analysis. No remarkable chemical compounds between tin and nickel were produced. The substrate atoms diffused into both surface layers, and a compound or a solid solution was formed. The iron diffusion was driven by the strong affinity between tin and iron. The results suggest the following two basic rules: I. When tin is the underlayer in direct contact with the iron substrate, the alloying of stacked tin and nickel layers hardly occurs. 2. When the nickel underlayer was very thin (e g submicron thickness), the substrate iron atoms can penetrate into the top tin layer through the intermediate one, but there is little evidence for the alloying of tin and nickel.     

含纳米Ni粉高温陶瓷涂层/GH202合金界面反应的研究

涂层失效一般是由涂层与基底界面的显微组织演变引起的,对高温下含纳米Ni粉的陶瓷涂层与合金组织的演变进行了研究,结果表明:陶瓷涂层/合金试样在900℃下进行真空扩散退火后,合金基底内在靠近界面的附近依次出现了Al2O3的晶间氧化物和针状TiN氮化物析出层;在长时间扩散过程中,纳米镍粉逐渐聚集长大,与合金基底在界面处融为一体,形成涂层与基体的咬合,使涂层与基体的结合趋向于冶金结合,具有抑制涂层失效的作用。     

电化学方法研究高温下氢在碳钢中的扩散

<正> 前言 研究氢在金属中的扩散与渗透,定量的方法主要有阴极过程量气法、电化学测量法、高真空测量法和核物理法。电化学测量法的设备简单,灵敏度高,测量方便、快速、准确,因而被广泛用于氢渗透研究,但到目前为止,一般都只用于温度低于100℃的测量;高真空测量法只适用于氢渗透速率大的体系,不宜用于温度低于200℃的测量。因此,对于100～200℃下氢在金属中扩散行为,目前还缺少合适的测定方法。本工作应用电化学测量法的原理,建立了一套测试装置,研究了100～200℃下氢在碳钢中的扩散行为。