Mg-Al合金微弧氧化陶瓷膜表面镀Ni层的生长过程及表征

研究镀Ni层相组成和微观结构,分析Mg-Al合金微弧氧化陶瓷膜表面化学镀Ni层的形成过程。结果表明,化学镀时间为1~20 min时,镀层厚度增长速度较快,20 min后,镀层厚度增长速度逐渐减缓。多孔陶瓷膜表面首先沉积一层尺寸为几微米的Ni颗粒,微小颗粒团聚长大逐渐形成直径十几微米的胞状体结构。相比于多孔陶瓷膜,化学镀Ni后,试样的腐蚀电位正移105 m V,腐蚀电流大幅度下降,耐蚀性提高。     

非贵金属活化预处理化学镀Ni包覆TiC陶瓷粉体的研究

采用非贵金属活化预处理对TiC陶瓷粉体进行化学镀前处理,预处理后通过常温超声波辅助化学镀方法成功制备了Ni包覆TiC陶瓷粉体,通过场发射扫描电子显微镜(FE-SEM)和能谱(EDS)研究分析了原始TiC粉体、非贵金属活化预处理后TiC粉体和Ni包覆TiC粉体表面形貌,探讨了化学镀Ni包覆TiC陶瓷粉体的生长机理.结果表明:非贵金属活化预处理后TiC陶瓷粉体表面出现了大量的缺陷(台阶),化学镀Ni包覆TiC陶瓷粉体表面Ni层覆盖完整、致密均匀;Ni颗粒的形核、长大和聚集的过程为:化学镀溶液中的反应物在TiC表面缺陷上吸附,发生氧化-还原反应沉积出Ni颗粒;Ni颗粒依附“线条状”突起以“线型”方式长大、弯曲、分叉和聚集,而后缠绕成“胞状”结构,犹如“缠毛线团”.“胞状”结构Ni颗粒不断长大聚集,最后成膜.     

高硅SiC_p/Al复合材料化学镀Ni-P合金层及其生长动力学（英文）

经Sn/Pd活化后,在SiC体积分数为65%的SiC_p/Al复合材料表面化学镀Ni-P合金,研究复合材料表面形貌及其对Ni-P沉积过程的影响,以及Ni和P原子间的结合方式。结果表明,Sn/Pd活化点分布不均导致Ni-P颗粒优先沉积在Al合金和粗糙的SiC表面以及腐蚀孔洞中,Ni-P合金膜具有非晶结构,其中Ni原子和P原子间依靠化学键结合。在形成连续的Ni-P合金膜之后,化学镀Ni-P合金不再受SiC_p/Al复合材料表面形貌及特性的影响,而是受化学镀本身控制,Ni-P合金膜遵循线性生长动力学,其活化能为68.44 k J/mol。     

低碳钢表面化学镀Ni-Zn-P合金镀层的沉积行为及沉积机理

目的通过研究低碳钢表面碱性化学镀Ni-Zn-P合金镀层的沉积行为及其沉积机理,对化学镀Ni-Zn-P有进一步认识。方法采用碱性化学镀方法,改变施镀时间在低碳钢表面化学镀Ni-Zn-P合金镀层。使用扫描电镜观察合金镀层的表面和断面形貌,用电子能谱仪分析镀层表面和断面成分。结果化学镀Ni-Zn-P合金镀层的形成过程是:固液界面形成原子团→原子团在能量较高的地方择优沉积→原子团累积生长→向周围延伸扩展→覆盖整个机体→形成完整镀层→均匀叠加生长。试样表面成分检测表明,施镀1~3 s内表面出现Ni元素,Ni质量分数在3 min时达到最大值75.93%,此后维持相对稳定;施镀1 min时表面出现P,P质量分数随施镀时间延长而逐渐增加,在30 min时达到最大值12.03%,此后维持相对稳定;施镀5 min时表面出现Zn,随着施镀时间的延长,Zn沉积量变化不大。表面和断面成分分析表明,化学镀Ni-Zn-P合金镀层的沉积过程不是Ni,Zn,P三种元素同时沉积,而是Ni优先沉积,然后Ni和P共沉积,最后Ni,Zn,P三种元素共同沉积。根据能斯特方程算得沉积电位E_(Ni~2+/Ni)=-0.337 V,E_(Zn~2+/Zn)=-0.906 V,两者的沉积电位相差较大,说明该化学镀条件下不能发生合金共沉积。结论推测化学镀Ni-Zn-P合金镀层是催化诱导还原反应沉积机理,即在镍还原诱导下引发的Zn共沉积。     

SiO 2基底上化学镀Ni-Mo-P薄膜的生长和形成机理

采用化学镀方法在SiO2/Si 基底上制备Cu互联线用阻挡层材料Ni-Mo-P薄膜。采用场发射扫描电子显微镜、电子分散能谱仪、原子力显微镜分析不同沉积时间样品的表面形貌和成分,并对Ni-Mo-P薄膜的形成过程进行研究。Ni-Mo-P薄膜的形成过程分为3个阶段：催化阶段,先前还原的Pd颗粒成为Ni还原的催化形核中心,诱导Ni沉积;覆盖阶段,Ni颗粒诱导Mo、P与之进行共沉积;自生长阶段,Ni-Mo-P薄膜共同沉积,颗粒生长。阐述了还原剂被氧化后产物为3-4PO 的的反应机理。     

压铸镁合金化学镀Ni-P的沉积过程

通过扫描电镜和GDA辉光放电光谱分析仪等手段，研究了压铸镁合金化学镀Ni-P的沉积过程，结果表明镁合金化学镀的前处理使基材表面呈现孔洞结构，活化形成比较平整的疏松网孔状MgF2和AIF3层：镁合金化学镀Ni-P的初始沉积过程，首先是Ni的还原析出，并不含P；随着Ni形核数量的增多和长大，有自催化能力的Ni层产生，镍磷共沉积开始：镀层中存在铬化物、氟化物与镀液成分以及Ni的混杂层。     

镍包覆氧化铝增强铁基复合材料的界面行为及其耐磨性

采用化学沉积法在Al2O3表面制备了Ni镀层,将所制得的Ni包覆Al2O3颗粒(Al2O3P@Ni)作为铁基体的增强颗粒,采用SPS法制备了镀镍氧化铝增强铁基复合材料(Al2O3p@Ni/Fe).通过优化化学镀工艺,使得Al2O3表面被Ni层均匀覆盖.Ni镀层呈典型的花椰菜状结构,尺寸为1～4 ～μm,施镀过程中镍首先...     

化学镀Ni—P合金

技术特点：非晶镀Ni—P合金通称为化学镀Ni—P合金．是近些年发展起来的一种表面处理技术。它利用镀液的自催化反应，无需通电即可在金属表面或非金属表面上沉积一层Ni—P合金。这种镀层致密、孔隙少，镀层结构为非晶状态．具有很好的耐蚀性。在某些介质中的抗蚀性优于不锈钢，     

铝表面预镀镍工艺的研究

研究了铝化学镀Ni－P前表面预镀镍的工艺。试验结果表明．经过预镀镍处理后,铝表面可获得镍沉积的催化表面．有效防止了在化学镀Ni－P槽液中置换反应的发生。文中指出,为了保证镀层与基体之间有良好的结合强度,并防止预镀镍溶液内出现氢氧化镍沉淀,预镀镍溶液内络合剂摩尔浓度应等于或略大于镍离子摩尔浓度的10倍．pH值必须控制在10～11之间。     

钨铜合金化学镀镍磷镀层在NaCI溶液中的腐蚀行为

采用化学沉积的方法在W—Cu粉末合金上成功地实现了化学镀Ni—P镀层,镀层表面光滑、致密,在结构上属于非晶态;经过25d的3．5mass％NaCI溶液浸泡研究表明：在浸泡的前16d中,化学镀Ni—P镀层的腐蚀速率逐渐增大,在16d之后腐蚀倾向有所降低;通过腐蚀失重实验得到Ni—P镀层的腐蚀失重小于W—Cu合金,说明化学镀Ni—P镀层可以对W—Cu合金起到保护作用。     

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.     

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。