Diffusion Bonding of Laser Surface Melted Nickel Alloy Material

Diffusion bonding studies were performed on Laser Surface Melted (LSM) Ni-Cr-Fe material. LSM generates metastable microstructures with extended solid solution. The rapid quenching associated with LSM generates a zone that is void of intragranular precipitates, consists of well-defined grain boundaries via intergranular carbides, and contains fine-grained material. Grain growth across the bondlineand precipitate morphology were studied as a function of laser beam power (energy density) and bonding temperature. LSM at low energy density produced excellent grain growth across the bondline even when bonding at low temperature.     

Calculation of Point Defects in NiAl Alloy

The potential functions of the F-S model for ordered high-temperature intermetallic compound NiAl with a B2 structure are constructed. Using the potential, the point defects properties were studied by molecuIar dynamics method, the results are in good agreement with that by EAM method and the experiment values. Meanwhile, the results clarify the experiments of two recovery stages in quenched NiAl alloy, and indicate that the two stages are corresponding to the recovery of Ni vacancies and of Al vacancies     

镁合金化学镀镍

镁合金在工业中的应用越来越广泛,通过化学镀镍可以克服镁合金耐蚀性和耐磨性差的缺点.介绍了镁及镁合金化学镀镍的原理/工艺的发展过程及研究现状,在此基础上指出了目前存在的问题和将来的发展方向.     

High-Temperature Salt Corrosion of a Heat-Resistant Nickel Alloy

Materials Science - We develop a heat-resistant corrosion-resistant alloy based on nickel and alloyed with rhenium and tantalum. This alloy is intended for the production of blades for a new...     

Protective Properties of Layers Formed on the Surface of Nickel

The polarization and impedance methods are used to study, in a 3% NaCl solution, the protective properties of films preliminarily formed on the surface of nickel in air, in HCl and H₂SO₄ vapors, and under the conditions of anodic polarization of the electrode in HCl solutions. It is shown that the protective properties of the films depend on the conditions of their formation.     

温度对NiAl合金纳米线应力诱发相变的影响

利用由Mishin等提出的嵌入原子势函数,本文进行了Ni/Al单晶纳米线应力诱发相变的分子动力学模拟。而且,本文使用了共同近邻参数(CNA)监测相变的形核与扩展。经过研究发现,在单轴拉伸的作用下,Ni/Al单晶纳米线发生了B2→L10的马氏体相变。本文还研究了温度对NiAl纳米线应力诱发相变的影响,发现随着温度的上升,相变转变应力逐渐减小,而相变形核区域也趋于分散。     

Characteristic Regularities in Condensation of Nickel Layers on the Surface of a Tungsten Single Crystal

Technical Physics Letters - Condensation and adsorption of Ni with a thickness from several tenths of a monoatomic layer to several hundred layers on the surface of a single-crystal W tip has been...     

镁合金化学镀镍层的性能研究

化学镀镍是镁合金保护的重要手段.为探讨化学镀镍对镁合金的保护效果,本文利用电化学极化曲线、X射线衍射和扫描电镜等手段研究了镁合金化学镀镍前处理方法及镀层性能.镁合金上化学镀镍层厚度达到15μm时已没有惯穿镀层的孔隙,200℃以上热处理可显著提高镀层结合力;由于镀层和镁合金间强烈的电偶腐蚀作用,在户外或潮湿环境中,化学镀镍对镁合金而言是一种有较大风险的防护方法.为获得更好的保护效果,多层化学镀或电镀与化学镀相结合是较好的选择.     

脱合金法制备纳米多孔镍材料研究进展

纳米多孔金属镍材料的研制成功,开拓了多孔金属新的应用领域。综述了脱合金法从Ni—Al合金中制备纳米多孔镍材料的必要条件,并十分析了脱元素法和脱相法各自的特点。脱元素法获得的纳米多孔镍的结构是三维无序内部互连通孔结构,而脱相法会产生原有的γ相或γ’相与多孔结构互相交织的网状结构,其中互通孔道大多为几百纳米宽。脱相法是个电化学控制的过程,脱元素法不需要加电压。同时,指出了纳米多孔镍基材料的应用领域及今后的研究方向。     

Convective Diffusion Of Water In Swelling Gelatin Layers

The literature concerning the swell of gelatin layers immersed in water is reviewed. It is shown that all of the published swell equations are effectively special cases of a general empirical rate equation. In an attempt to establish mechanism, a hypothetical scheme is proposed involving a concentration-dependent intrinsic diffusion coefficient, a linear adsorption isotherm relating the free and sorbed water concentrations, a constant ratio of final swell to dry thickness, and a proportionality between the local swell and the sorbed water con-centration. It is shown for this hypothetical scheme that the convective one-dimensional diffusion equation can be linearized and solved exactly for the appropriate boundan/ and initial conditions. It is also shown that the general solution takes a particularly simple form for moderately long times after immersion. Experimental sivell data are then used to deduce values for the intrinsic diffusion coefficient which compare favourably with the self-diffusion coefficient of water. It is also shown that an exact solution to the associated problem of desorption of water from the fully swollen layer can be obtained by a simple rearrangement of the boundary and initial conditions.     

High Temperature Deformation of a β''''(NiAl) Precipitation Strengthened Ferritic Alloy

A β'(NiAl) precipitation strengthened ferritic Fe-19Cr-2Al-4Ni alloy was tested under low cycle fatigue and creep at elevated temperatures. The dislocation microstructures developed were examined by transmission electron microscopy (TEM). The deformation behavior of the alloy was interpreted in terms of dislocationprecipitate configurations and interactions.fatigue deformation.     

铝合金化学镀镍工艺

１工艺流程 有机溶剂除油→吹干→化学除油→水洗→出光→水洗→两次浸锌→水洗→化学镀镍→水洗→烘干 （１）有机溶剂除油用汽油或其他有机溶剂除去零件表面的大量油污。 （２）化学除油、碱蚀用 ５０～６０ ｇ／Ｌ的 ＮａＯＨ溶液,在 ５０～６０℃的条件下浸蚀２～３ｍｉｎ,除去零件表面的少量油污和氧化膜,并对铝合金表面产生轻微的腐蚀以提高镀层结合力。 （３）出光在 １：１的 ＨＮＯ３中浸渍 ３０～６０ｓ,用以除去碱蚀后在零件表面形成的挂灰,产生光亮表面。 （４）两次浸锌通常由于第１次所产生的锌层比较粗糙,附着力较差,…     

电镀镍磷合金工艺初探

电镀镍磷与化学镀镍磷相比具有沉积速度快、镀液温度低、稳定性高、可以镀厚镀层、成本低等优点,但与常规电镀相比镀液和镀层性能不稳定,电流效率低.对几种电镀镍磷合金镀液进行比较,通过中性盐雾试验,全浸泡腐蚀试验,镀层孔隙率、结合力和硬度测试,得到溶液的主要成分为硫酸镍、氯化镍、次亚磷酸钠、硼酸、氟化钠,并研究了次亚磷酸钠的含量和阴极电流密度对镀层硬度和耐蚀性的影响.结果表明,随着次亚磷酸钠含量的增加,镀层的耐蚀性增加,当次亚磷酸钠含量为50 g/L、电流密度为5 A/dm2时,镀层的硬度最高(492 HV);镀层中磷的含量为12.1%,沉积速度为54 μm/h,热处理后硬度可达916 HV.使用次亚磷酸盐型镀液,镀层结晶细致、光亮、结合力好、硬度高、沉积速度快.     

新型合金代铬刷镀层的组织及强化机理的研究

采用Ｘ射线衍射仪，透射电镜和扫描隧道显微镜等手段对新型代铬镀层（Ｎｉ－Ｆｅ－Ｗ－Ｐ－Ｓ）相结构及组织进行了研究，并初步探讨了镀层的强化机理。研究表明，Ｎｉ－Ｆｅ－Ｗ－Ｐ－Ｓ合金镀层的组织是由含Ｆｅ、Ｗ、Ｐ、Ｓ的镍基固溶体和在其上弥散分布的金属间化合物Ｎｉ_３Ｆｅ所组成，镍基固溶体处于非晶和微晶的混合状态，合金镀层的镀态硬度为ＨＶ７００～７５０，在３００℃退火时。硬度达到最大值ＨＶ９００～９５０，其强化机理主要是微晶的晶界强化和Ｎｉ_３Ｆｅ的弥散强化。     

反应磁控溅射制备氮化钽扩散阻挡层的研究

采用反应磁控溅射在硅衬底上制备了TaN薄膜,研究了氮分压、溅射功率及衬底温度对薄膜晶体结构、表面形貌和电学性能的影响。结果表明,晶体结构随工艺参数的改变发生变化,GIXRD图谱衍射峰强度随溅射功率和衬底温度的增加而增强,氮气分压的增加使择优取向向(111)晶面偏移;TaN薄膜的表面形貌与溅射功率和氮气分压密切相关,与衬底温度的关系不大,其粗糙度随溅射功率的增加而增大,随氮气分压的增加而减小;TaN薄膜的方块电阻随溅射功率的增加逐渐减小,随氮气分压的增加逐渐增大,温度对方块电阻的影响不大;对Cu/TaN/Si互联体系热处理后发现TaN薄膜具有优异的阻挡性能,在600℃时依然可有效阻止Cu向Si的扩散。     

Hydrogen-Induced Cracking of Two-Phase Alloy of Ni3Al＋NiAl

Hydrogen-induced cracking (HIC) of two-phase alloy of Ni_3Al+NiAl was in situ investigated using a WOL (wedgeopening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scan-ning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was K_(IH)=15.7 MPa·m~(1/2),and (da/dt)Ⅱ=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially withinthe NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of24.7×10~(-4)%, hydrogen-induced crack initiated and propagated preferentially along the Ni_3Al/NiAl interfaces, result-ing in interphase fracture.     

铝合金直接电镀镍工艺的研究

通过试验，找到了一种配体体系和适当的工艺，实现了在铝合金上直接电镀镍，分析了各种工艺参数对镀层质量的影响。结果表明，该工艺操作简单，镀层外观，硬度和结合力等完全可以与浸锌工艺媲美。研究还表明pH值控制是本工艺的关键。     

光亮镀镍液中杂质对镀层性能的影响与去除

光亮镀镍液含有硫酸镍、氯化镍、硼酸及光亮剂等 ,含镍 50～80ｇ/Ｌ ,氯化物 12～ 2 0ｇ/Ｌ ,硼酸不少于 3 5ｇ/Ｌ。长时间施镀后 ,杂质离子和其他副产物逐渐积累 ,当达到一定浓度时 ,使沉积速度降低 ,镀层的孔隙率增大 ,延展性下降。杂质对镀层的不良影响是常见的电镀故障 ,杂质分为三类 ,即有机杂质、无机杂质、机械杂质。1　有机杂质1 .1　影　响有机杂质主要是带入槽内的油脂、表面活性剂、添加剂分解物 ,对镀液和镀层的质量产生不利的影响。从直观上看 ,表现为镀层的光亮度降低、局部发花、起污斑 ,而且镀层的应力增加、脆性增大、韧性…     

Mg-13Li-5Zn合金化学镀镍研究

对Mg-13Li-5Zn合金化学镀镍进行了研究,确定了合适的前处理工艺,并采用X射线衍射、中性NaCl浸泡电化学测试及硬度测试等方法分析了镀层性能.结果表明,施镀2 h后镀层厚度约20 μm;镀层均匀、致密、无明显缺陷;X射线衍射分析表明镀层组织为单一的镍相;利用能谱测得磷含量为6%(质量分数);其自腐蚀电位约为-0.40 V,且在5%NaCl溶液中浸泡48 h无腐蚀孔出现,可以给镁锂合金提供一定的保护.     

钛合金化学镀镍层结合力影响因素探讨

钛合金化学镀镍层结合力的大小直接影响到镀件的使用寿命,镀层的结合力受到众多因素的影响.主要研究了浸蚀活化、预镀镍及镀镍后热处理对钛合金TC4与化学镀镍层结合力的影响.结果表明:HF和HCl的比例是影响钛合金表面活化的重要因素,采用26 mL/L HF,58 mL/L HCl活化可以获得新鲜的钛合金表面;浸蚀活化后预镀镍再化学镀镍,可得到结合力良好的镀层;镀层经300℃热处理1 h后与基体的结合力显著提高.