铅镉二元合金的共沉积添加剂

采用线性电位扫描法对铅、镉二元合金共沉积中适用的添加剂进行了筛选,研究了不同种类添加剂对铅、镉电沉积的影响,并分析讨论了添加剂的作用。通过对合金镀层中铅、镉元素含量的测定和合金镀层对应的阳极溶出极化曲线的测试和分析,证明了合金镀层中的铅、镉是一种单金属混合物。研究结果表明,采用本合金电沉积技术可获得镀层性能良好的、不同镉含量的铅、镉二元合金镀层。     

电沉积钨合金镀层的研究现状与应用进展

介绍了电沉积钨合金镀层最常见的几种二元系、三元系及多元系合金类型,概述了在许多重要领域的研究和应用的现状与进展,分析了元素种类和含量对钨合金镀层硬度、耐磨性、耐蚀性和热稳定性等性能的影响,并详细探讨电镀工艺中镀液组成、温度、pH值、电流形式以及不同的热处理过程对钨合金镀层晶态与非晶态结构的影响,重点论述了钨合金镀层的耐蚀性与其晶体结构的关系,最后提出了今后钨合金镀层及其耐蚀性研究与应用的重要方向.     

《表面技术》2009年第1期摘要及目次

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     

基于人工神经网络预测Ni-W合金镀层的硬度和耐腐蚀性能

目的预测Ni-W合金镀层的硬度和耐腐蚀性能,优化Ni-W合金镀层的电沉积工艺。方法在柠檬酸-硫酸盐溶液体系中直接沉积制备Ni-W合金镀层,并将实验所得镀层数据作为学习样品,利用BP神经网络对建立了Ni-W合金电沉积过程参数对镀层硬度和腐蚀电流密度之间的映射关系。结果低碳钢表面所沉积的Ni-W合金镀层表面均匀致密,与基体结合良好,能够有效地对基体起到保护作用。第二隐层的加入使得3-7-15-2四层网络达到网络收敛的训练次数(1 215 365次)远小于3-7-2三层网络的训练次数(239 950 000次)。四层网络预测所得镀层的硬度和腐蚀电流密度与实验值十分相近,其相对误差≤5.03%。结论 BP神经网络能够准确建立电沉积Ni-W合金镀层的工艺条件和目标性能之间的映射关系,在本文所用的沉积体系和参数范围内,Ni-W合金镀层的显微硬度在296~982HV之间,其硬度最大时所对应的电沉积工艺条件为:p H=7.2,电流密度8 A/dm2,WO42+浓度为0.46 mol/L。Ni-W合金镀层的腐蚀电流密度在7.3~100μA/cm2范围内。镀层耐蚀性能最好时,即镀层腐蚀电流密度最小时的电沉积工艺条件为:p H=6.4,电流密度0.36 A/dm2,WO42+浓度为0.34 mol/L。     

稀土对机械镀无结晶形成过程及镀层性能的影响

采用机械镀方法制备了锌基稀土无结晶镀层,用扫描电子显微镜(SEM)、X射线荧光光谱分析(XRF)等研究了稀土添加对机械镀无结晶镀层形成过程及镀层特性的影响.结果表明,稀土金属盐复合添加剂能影响无结晶镀层形成时金属微粉的集聚、吸附和沉积特性,使金属粉趋于面状吸附一沉积,改善了镀层的形成条件.机械镀锌基稀土合金镀层外观平整、光亮,密度、显微硬度、耐腐蚀性和电化学特性明显优于传统机械镀锌层.     

化学镀 Ni-Mo-P 合金镀层的组织结构与防垢性能研究

目的采用材料测试方法和防垢实验,研究不同工艺条件下的化学镀Ni-Mo-P合金镀层的组织结构与防垢性能。方法在化学镀Ni-P镀层基底上,添加含有钼酸根离子杂多酸盐,在不同工艺条件下化学沉积Ni-Mo-P合金镀层,研究化学镀Ni-Mo-P合金镀层的表面形貌和组织结构,分析镀液中硼酸含量和钼酸铵含量对镀层沉积速率的影响,观测镀层在结垢实验后的表面形貌并分析结垢速率。通过SEM,XRD和EDS对化学镀Ni-Mo-P合金镀层的表面形貌和组织结构进行检测,研究在酸性镀液中硼酸含量对化学镀Ni-Mo-P工艺条件的影响。采用防垢实验测试化学镀Ni-Mo-P合金镀层的防垢性能。结果在化学镀Ni-Mo-P过程中,钼酸根离子杂多酸盐具有稳定作用。化学镀Ni-Mo-P合金镀层的化学沉积镀液的最佳工艺条件为:Ni SO4·6H_2O 16.5 g/L,Na H_2PO_2·H_2O 20 g/L,钼酸钠0.5~0.8 g/L,硼酸2 g/L,乙酸钠7.5 g/L。化学镀Ni-Mo-P合金镀层的结垢速率明显低于化学镀Ni-P镀层,具有良好的防垢能力,形成了非晶态的镀层。结论采用化学镀Ni-P镀层基底上沉积得到非晶态的Ni-Mo-P合金镀层,硼酸具有调节镀液p H值和络合作用,非晶态的Ni-Mo-P合金镀层平均结垢速率最小值为0.58μm/h,具有良好的阻垢能力。     

Ni-W-B电沉积涂层及微观结构研究

镀Cr层因为镀液对环境的污染,使Ni－W－B三元素合金抗磨和抗蚀镀层研究得到迅速发展。镀层沉积条件为碱性镀液,不溶性电极。共沉积合金镀层包含40wt％W和1wt％B,为非晶或部分非晶结构。合金沉积层在镀层均匀和反射性方面均优于Cr镀层。在各种酸性镀液（盐酸、硫酸、磷酸）条件下将Ni－W－B合金镀层性能与镀Cr利镀Ni层进行了比较。在各种条件下,Ni-W-B合金镀层具有最好的性能。本研究中使用的是铜底材。     

［例33］三元牺牲阳极镀层在油田管道防腐中的应用

正阳极镀层电位相对于被涂覆的金属本体更负。当内、外表面涂覆阳极镀层的金属管道处于腐蚀介质中时,阳极镀层会失去电子,成为电化学腐蚀的阳极,从而使金属得到保护。三元牺牲阳极镀层主要成分为Zn-Al-Mg合金,其中少量的Al和Mg使得极化初期产生较大电流,极化稳定后所需保护电流小,由成分较多的Zn来提供。该镀层具有对碳钢驱动电位不高、电流效率高、使用寿命长、成本低的特点,适合应用于高矿化度、低电阻率的油田采出液中。三元牺牲阳极溶解涂覆在金属短节内外壁表面,将其内部引入网状骨架以防止阳极镀层脱落,形成三元牺牲阳极镀层保护器,设计寿命在4年以上。该装备应用于塔河油田井下注水管道6年以来,管道     

镁合金表面制备高红外发射率和高导电率热控膜层

目的通过电沉积方法在镁锂合金表面制备具有高红外发射率以及高导电率的镀层,满足其在太空中散热以及电磁屏蔽的需要。方法通过前处理工艺(碱洗→酸洗→预钝化→化学镀镍磷→电镀铜)提高镁锂合金基体的耐蚀性能以及与后续镀层的结合力,并在此镁锂合金前处理工艺的条件下,电沉积多孔Zn-Ni合金镀层。通过热循环测试和电化学方法评价各镀层的电化学腐蚀行为和各镀层之间的结合力。结果各镀层之间的结合力良好,化学镀Ni-P层、电镀Cu层和多孔Zn-Ni层的耐蚀性能均优于镁锂合金基体,该组合镀层的协同作用可以有效地保护镁锂合金基体,提高其耐蚀性。结论最外层多孔Zn-Ni合金镀层主要由Ni2Zn11、NiO、NiS组成,其红外发射率为0.90,电阻率小于0.01 m?/cm。这表明多孔结构可以有效提高金属合金镀层的红外发射率,并保持合金镀层的高导电性。     

稀土对硫酸盐体系电沉积Zn-Fe合金阴极极化的影响

为了深入地探讨Zn-Fe合金镀层的电沉积机理,实验在了三电极体系下,采用动电位法测定硫酸盐体系电沉积Zn-Fe合金镀层的阴极极化曲线,探讨了该合金镀层的电沉积机理,以及镀液成分和稀土盐的加入对电沉积阴极极化的影响.通过实验发现,Zn-Fe合金镀层的沉积属于异常共沉积,结果表明镀液中加入稀土盐Ce2(SO4)3后,对Zn-Fe合金镀层电沉积的阴极极化行为有较大影响.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.