B30铜镍合金在海水中的电化学行为

B30铜镍合金具有优良的耐海水腐蚀性能,但在海水中形成的表面膜对其自身的电化学行为有影响,过去对此研究不多.采用交流阻抗、线性极化、动电位极化、循环阳极极化等方法研究了B30铜镍合金表面在海水中形成的氧化膜对其自身腐蚀电化学行为的影响,采用原子力显微镜(AFM)对氧化膜的结构进行了分析.结果表明:B30铜镍合金在海水中浸泡72 h后,表面能够生成一层完整致密的氧化膜;表面膜使B30铜镍合金在海水中的阻抗值随浸泡时间的延长先增大后减小,而且能够降低其极化电流密度以及瞬时腐蚀速率;随着浸泡时间的延长,B30铜镍合金在海水中的点蚀倾向加重.     

铜镍合金的强韧化行为及其微观机制的研究进展

近年来,高性能铜镍合金因其具有优异的性能成为了研究热点.本文综述了一些高强韧铜镍合金的研究进展,重点对该系列铜镍合金的强韧化行为及其微观机制进行了讨论与分析.最后给出了高强韧铜镍合金特别是多主元高强铜镍合金的发展趋势.     

离子轰击铜-镍合金影响层的研究

利用最小二乘法计算机拟合法,研究了铜-镍合金在离子轰击下,其表面铜、镍元素的浓度变化。表面分析用扫描俄歇微探针PHI-590型进行。研究证明:在影响层内元素的分布是不均匀的,影响层厚度大于15(?)A,并且这种不均匀的分布随轰击离子能量变化而变化。在停止轰击的40分钟内,未见表面元素变化。从铜-镍合金的俄歇谱分析可知,合金能带的刚性能带理论并不适合本研究系统。     

三价铬体系电镀铬-镍合金工艺

采用工业铬酐-甲醇还原法制备三价铬主盐,给出了电镀铬-镍合金工艺配方与工艺规范并对镀层性能进行了测试.电流密度对镀层的成分和性质有较大的影响.含铬量63%左右的铬-镍合金镀层具有较好的硬度和耐蚀性.双层镍作中间镀层的装饰性铬-镍合金试件经16 h铜加速盐雾试验(CASS)后,外观未出现不良现象,镀层显示了较好的耐蚀性能.     

AFM扫描图像重构算法的改进

针对原子力显微镜（AFM）纳米成像中存在的失真问题,研究了通过探针建模实现AFM扫描图像重构方法.目前探针盲建模算法在重构AFM图像时存在较大误差,因此提出基于探针模型预估计的AFM扫描图像重构方法.该方法采用分区探针针尖建模,并通过基于该探针模型的反卷积运算实现AFM扫描图像重构,获得比较接近真实形貌的AFM扫描图像.文中介绍了算法的具体步骤,通过仿真和实验结果证明,该方法能够有效降低AFM图像重构时引入的误差,得到的图像更能反映样品表面真实的形貌.     

B30铜镍合金管材表面膜层演化及失效行为研究进展

B30铜镍合金管材由于其良好的耐海水腐蚀性能被广泛应用于船舶换热设备及海水管系,但在复杂工况下,服役过程中频繁发生膜层失效导致的管材腐蚀泄漏问题。本研究分析了B30铜镍合金管材表面膜层的耐蚀机理及演化过程,阐述了铜镍合金表面膜层失效模式及影响因素,并提出了B30铜镍合金管防腐措施及使用建议。     

利用典型Si(100)微结构对原子力显微镜探针参数进行表征

利用各向异性化学湿法刻蚀工艺在Si(100)上加工了具有本征侧墙角(54.73°)的典型微机电系统(MEMS)梯形结构.用该微结构作为线宽测试结构,对其进行了原子力显微镜(AFM)和扫描电子显微镜(SEM)线宽和轮廓的比对测量.并对AFM探针和样品耦合效应进行了研究,提出了AFM探针参数动态表征的模型,基于几何模型对线宽和轮廓测量中探针针尖形状和针尖位置参数进行了表征,提出了用曲率半径、安装倾角、扫描倾角和针尖半顶角来对原子力显微镜探针针尖进行表征.该方法是对现有AFM探针表征模型的改进和完善.     

温度对70/30铜镍合金在海水中腐蚀的影响

本文介绍了旨在研究温发对70/30到镍合金上发现的薄膜的影响的试验结果。结果表明,70/3)铜镍和66/30/2/2铜镍合金的电位解释了70/30钢镍合金在低温下较低的抗冲击腐蚀性能,这是在温度高于10℃时观察到的。在低于10℃的温度下,认验时电位在-200毫伏(SCE)左右几乎是恒定的。电位向正的方向移动与70/30我,铜镍合金表面膜中富铁有关。对66/30/2/2铜镍铁锰合金来说,可测得表而膜的成分与温度没有明显的关系。从90/10铜镍合金中观察到电位没有变化,甚至在长时间的试验后也是如此。70/30铜镍合金的结果解释了这种台金在低温下较低的抗冲击腐蚀性能,这是在英国有色金属工艺中心以前的研究中观察到的。     

90/10铜镍合金海水管路直流杂散电流腐蚀及控制研究

针对某船90/10铜镍合金海水管路系统异常快速腐蚀问题,采用失重法、电化学法、微观形貌分析等方法研究了90/10铜镍合金海水管路系统直流杂散电流腐蚀规律,对比分析了直接排流法和牺牲阳极保护法对直流杂散电流腐蚀控制的效果。结果表明,90/10海水管路直流杂散电流腐蚀速率随着杂散电流强度增加而线性增加,晶界优先发生腐蚀溶解;直接排流法和牺牲阳极保护法均可抑制直流杂散电流腐蚀,但牺牲阳极保护法对强直流杂散电流腐蚀防护效果有限,直接排流法可对90/10铜镍合金海水管路直流杂散电流腐蚀进行有效保护。     

铜镍合金在NaCl溶液中点蚀行为的研究

对铜镍合金BFe30-1-1在NaCl溶液中出现的点腐蚀行为进行了研究.首先测试其在不同pH值的0.5 mol/L Nacl溶液中的阳极极化曲线以确定点蚀电位,并在点蚀电位之上进行恒电位腐蚀.通过原子吸收光谱测定腐蚀后溶液中的Cu2 和Ni2 含量,采用扫描电镜进行形貌观察以及分析试样断面的微区成分,并对点蚀坑内的腐蚀产物进行X射线衍射分析,以了解不同条件下铜镍合金的点腐蚀行为.结果表明,BFe30-1-1合金在酸性和弱碱性的0.5 mol/L NaCl溶液中的腐蚀规律基本相似;在强碱性溶液中的低电位下,合金表面可以形成较稳定的钝化膜,因而耐腐蚀性能较好;铜镍合金BFe30-1-1的点蚀坑内发生了脱镍腐蚀.     

Influence of sodium chromate and dodecylamine on enhanced dissolution behavior of Cu—Ni alloy induced by AFM tip scratching

The influence of two inhibitors sodium chromate and dodecylamine on enhanced dissolution of Cu–Ni alloy initiated by atomic force microscopy (AFM) tip scratching in 1.5 M NaCl and 0.01 M HCl was investigated. The lateral force traces and force versus distance curves were measured by AFM in distilled water without or with inhibitors to investigate the influence of inhibitors on physical characters of sample surfaces. The results indicated that enhanced dissolution caused by AFM tip scratching was inhibited by adding sodium chromate or dodecylamine into the corrosive solutions, but their inhibition mechanisms are different. The inhibition effect of sodium chromate is due to its oxidation ability to repair the destroyed protection film and the increase of rigidity of metal surface resulted from the formation of oxide film containing Cr elements. On the other hand, the inhibition effect of dodecylamine is due to the organic adsorption film on metal surface to weaken the friction forces between the tip and the sample and to elevate the ionization energy of metal.     

Alloy induced inhibition of fatigue crack growth in age-hardenable Al–Cu Alloys

Environmental fatigue crack propagation (EFCP) is alloy-inhibited in under aged Al–Cu–Mg and peak aged Al–Cu–Li alloys stressed in pure aqueous chloride solution. Counter to H diffusion and H-embrittlement rate limited step considerations which predict fatigue crack growth rate (da/dN) to be either independent of fatigue loading frequency (f) or increase with decreasing f, da/dN declines with decreasing f. The mechanism for such alloy induced inhibition and decreasing da/dN with decreasing f is reduced crack tip H production and uptake due to stabilization of the native aluminum passive film resulting from: (1) dissolution of anodic Cu-containing GP zones or precipitates (Al₂CuLi or Al₂CuMg) by dealloying, (2) crack surface Cu enrichment, and (3) enhanced crack wake cathodic reaction kinetics on Cu enriched sites that increase crack solution pH. Peak aged Al–Zn–Mg–Cu alloy 7075 does not exhibit alloy induced inhibition because the predominant anodic phase, Mg(Cu,Zn)₂, does not provide a source for Cu surface enrichment. Alloy induced inhibition is similar to ion-assisted inhibition by molybdate or chromate addition into bulk chloride solution which provides an alternate path to stabilize a crack tip passive film. Both alloy-induced and ion-assisted inhibition of EFCP are promoted by reduced f and crack tip strain rate which favor repassivation of the crack tip passive film over film rupture.     

SURFACE ALLOYING OF MILD STEEL BY LASER MELTING OF AN ELECTROLESS NICKEL DEPOSIT CONTAINING CHROMIUM CARBIDES

It is possible to realize surface alloys by laser melting an electroless nickel layer containing chromium carbide particles predeposited on a mild steel substrate. By this way the surface alloy is expected to have not only a high nickel content but also an important chromium content in order to improve the corrosion resistance. The presence of chromium in solid solution results from the dissolution or melting of the carbide particles. Typical laser solidification microstructures are obtained. Dendrites consist of an austenitic Fe-Ni-Cr solid solution and interdendritic regions are constituted by an eutectic mixture containing the same austenitic solid solution and complex Fe, Ni, Cr carbides and phosphides. In comparison with a surface alloy obtained by laser melting of an electroless nickel layer without carbide particles, the corrosion resistance was slightly improved in saline aqueous solutions. The limited effect was due to the fact that the final chromium content in the present experimental conditions was not as high as that initially expected.     

Nickel Oxide Interface for Xerographic Selenium Photoreceptors on Flexible Nickel Foils

The paper reports on a method to produce a nickel oxide interface for xerographic selenium alloy photoreceptors on flexible nickel foils. The process consists of an etching treatment in phosphoric acid catalyzed by small amounts of Pd or Pt on the surface and a subsequent electrochemical treatment in a Na₂Cr₂0₇ solution. The catalytic effect of Pd and Pt on the nickel dissolution in phospheric acid is investigated and explained on the basis of electrochemical principles. The etched nickel surface provides excellent adhesion of the photoconducting layer to the nickel substrate. In the subsequent electrochemical anodization treatment, a several hundred A thick nickel oxide layer is formed which reduces electron injection from the interface.     

Behavior of nickel in methanol water sulfuric acid solution

The electrochemical behavior of nickel in water-methanol-acid solutions has been investigated; the concentration of the three constituents of the solution have been extensively varied. The mechanisms of Ni dissolution and passivation seem to be the same as in water solution; the previously proposed model is well satisfied by the experimental results. Methanol seems to act as an inhibitor of the free corrosion of nickel, while water is the main passivating agent. Both active corrosion and passivation are diffusion controlled reactions: their rates in the presence of small amounts of water, are lowered.     

Electrochemical behavior of nitinol alloy in Ringer's solution

Corrosion behavior of Nitinol (nickel titanium) alloy has been examined in physiological Ringer's solution by means of electrochemical techniques (open-circuit potential measurement, potentiodynamic and potentiostatic polarizations) and capacitance measurements. The results show that the passive film is stable at open-circuit condition, but many of anodic current transients are observed at potentiodynamic and potentiostatic polarizations. The thickness of passive film decreased because of the occurrence of dissolution.     

Effective inhibition of nickel release by tantalum-implanted TiNi alloy and its cyto-compatibility evaluation in vitro

Titanium–nickel (TiNi) shape memory alloy is modified with tantalum (Ta) plasma immersion ion implantation (PIII). Scanning electron microscope (SEM), atomic force microscopy (AFM), inductively coupled plasma mass spectrometry (ICP-MS), methyl-thiazol-tetrazolium (MTT), and cell culture are adopted to evaluate the surface morphology, roughness, Ni release, in vitro cytotoxicity, and cell behavior of TiNi and Ta-implanted TiNi (Ta–TiNi) alloys. Results showed that the surface became rougher and was covered by ordered and uniform grains after Ta implantation. Ni release was averagely inhibited by Ta–TiNi to up to 60% of that in unmodified TiNi alloy within 30 days. MTT assays demonstrated that Ta–TiNi sample allowed greater degree of cell proliferation for both smooth muscle cell and osteoblasts, indicating excellent protection and cyto-compatibility. A negative correlation was observed between Ni release and cell proliferation. Analysis of the cell morphology revealed healthy cells extending on the alloy surface, which indicated that TiNi alloy had good cyto-compatibility despite the initial Ni dissolution, but the implanted Ta would endow traditional TiNi alloy much lower Ni release, improved cyto-compatibility and other potential merits.     

Heat treating of a ring rolled Ni–Fe–Cr superalloy

Abstract

Haynes HR-120 alloy (UNS N08120) is a nickel–iron–chromium alloy that exhibits high strength at elevated temperature and resistance to carburising and sulphidising environments. These properties make this alloy suitable for the production of components of land based turbines, including rings. Manufacture and heat treating of such rings require strict control of the processing variables, such as temperature and deformation ratios, as well as the time and temperature of the solution treatment, due to their effect on microstructure and mechanical properties. It is common practice to treat this alloy at temperatures above 1100°C to promote dissolution of undesired particles and recrystallisation of deformed structures, but it has been found that grain coarsening can occur during treatment. The present work presents the results of a series of solution heat treatments that were performed within a broad range of temperatures on industrial ring rolled pieces. It was found that the increment in time and temperature enhances the dissolution of intergranular precipitates that result in the improvement of mechanical properties, but grain coarsening is observed to occur when the material is treated for long times and high temperatures. The best combination of mechanical properties and grain size was obtained by treating the material for half an hour at 1050°C.     

铈离子对高强铝合金应力腐蚀开裂的缓蚀作用

基于慢应变速率拉伸实验(SSRT),采用恒电流极化、电化学噪声(ECN)与电化学阻抗(EIS)等方法,研究7A04铝合金在3.5%(质量分数)NaCl水溶液中的应力腐蚀开裂(SCC)行为以及Ce~(3+)对其SCC的缓蚀作用,探讨Ce~(3+)对裂纹孕育与发展过程的抑制机理。结果表明:无论是阳极还是阴极极化,均会促进7A04的SCC倾向,前者增加了裂尖的阳极溶解,后者则加速了裂尖的氢脆效应。Ce~(3+)的加入能延缓7A04的SCC断裂时间,但其有效性仅限于裂纹的萌生阶段。由于Ce~(3+)能够抑制铝合金表面的亚稳态点蚀发育和长大,因而使裂纹的孕育时间显著延长,降低了SCC的敏感性。不过一旦裂纹进入扩展阶段或者试样表面有预裂纹,则由于Ce~(3+)很难迁移到裂纹尖端或在裂尖区难以成膜,不能对裂纹的生长起到有效抑制作用,因而无法降低7A04的SCC发展速率。SEM分析表明7A04铝合金光滑试样SCC主要源于亚稳态或稳态点蚀的诱导作用。     

Determination of mechanical properties of electroplated Ni thin film using the resonance method

This paper addresses a relatively simple method of measuring the mechanical properties such as Young's modulus and residual stress of electroplated Ni thin film using the resonance method of Atomic Force Microscope. Thin layer of nickel to be measured is electroplated onto the tip side of AFM silicon cantilever and plating thicknesses were measured at the end of each plating step. The measured Young's modulus of nickel at the end of each plating step ranged from 148.04 GPa to 159.90 GPa with the maximum standard deviation of 3.47. The end deflection of electroplated AFM cantilever is also measured as a function of the plated Ni thickness, which is converted into the film stress by appropriate mechanics.