正交试验优化电沉积 Ni-Cr 泡沫合金工艺

目的获得电沉积Ni-Cr泡沫合金的最佳工艺参数。方法采用正交实验法研究镀液成分等工艺参数对镀层沉积速率、厚度以及合金中Cr含量的影响,并利用扫描电子显微镜等测试手段对镀层横截面厚度等镀层指标进行了考察。结果阴极电流密度为28 A/dm2,镀液pH值为2.0,镀液温度为25℃,CrCl3·6H2O的质量浓度为125 g/L,配位剂与Cr3+摩尔比为1.8时,电沉积60 min能够获得表面光亮平整的Ni-Cr合金镀层,镀层厚度为24.09μm,沉积速率为0.4198 mg/(cm2·min),镀层中Cr的质量分数为14.76%。结论镀液温度在25~40℃范围内,对Ni-Cr合金镀层厚度、沉积速率的影响最大;镀液中CrC13·6H2O浓度、配位剂与Cr3+的摩尔比两个因素,对合金镀层中Cr含量的影响较大。     

碳纳米管／锡基轴瓦合金复合减摩镀层的制备

采用复合电沉积方法在铜基轴瓦合金的表面制备碳纳米管/锡基轴瓦合金复合减摩镀层,研究了电沉积工艺参数对碳纳米管/锡基复合镀层的组织与性能的影响.结果表明,当阴极电流密度为1.5A/dm2,镀液中碳纳米管的质量浓度为2 g/L、镀液的pH值为1时,镀层生长良好,碳纳米管分布均匀.     

Preparation of Ni/CrAI Coatings on T91 Steel by Composite Electrodeposition

采用复合电沉积法在T91钢表面制备Ni/CrAl镀层,研究了CrAl微粒在镀层中的含量与搅拌强度、镀液pH值、电流密度及温度的关系,确定最佳工艺参数为:电流密度2.5～4.5 A/dm2,pH值4～4.5,温度30℃.采用该工艺制备了较高CrAl含量的复合镀层,并对工艺参数影响复合电沉积的机理进行了简单探讨.     

电沉积NiP非晶态合金的影响因素

本文研究了镀液浓度、温度、阴极电流密度、沉积层厚度以及不同基体材料等因素对沉积Ni-P非品态合金的影响.用X射线衍射仪,透射电子显微镜,电子探针显微分析仪等测定所得沉积合金的结构与组份.观察到在一定镀液浓度范围内,镀液的温度、电沉积时阴极电流密度,几种不同基体材料以及沉积层的厚度对是否获得非晶态合金影响均不明显,影响的关键因素是镀液中的Ni与P的比值.     

ZnSe薄膜电沉积工艺条件的研究

采用电沉积方法制备了ZnSe薄膜,研究了电沉积工艺参数,包括镀液的主盐离子浓度、配合剂浓度、pH值及电流密度等对膜层的影响.通过正交试验对上述各参数进行优化,以寻求最佳的工艺条件,得到最佳制备条件为:电流密度6.0mA/cm2,柠檬酸钠14.71g,pH值3.5,Zn2 /SeO2-3浓度比200:1,温度65℃,时间8min.在此条件下制备了薄膜样品,并用扫描电镜、EDAX能谱仪对镀层进行了表征,其结构均匀致密,Zn/Se化学计量比为1/1.01.     

AZ91镁合金表面制备Ni-SiO2纳米复合电镀层的工艺研究

采用复合电沉积技术在AZ91镁合金表面制备Ni-SiO2纳米复合镀层,并研究各工艺参数对镀层的影响,从而得出最佳工艺.研究结果表明:在镀液中纳米SiO2的添加量为20 g/L,阴极电流密度为1.0 A/dm2,镀液温度为50℃,活性剂A的添加量为1.0 g/L,pH为5～6的条件下,经过20～30 min电沉积,可获得均匀、平滑的镀层,镀层的显微硬度与耐蚀性最佳.     

T91钢表面复合电沉积Ni/CrAl镀层的工艺研究

采用复合电沉积法在T91钢表面制备Ni/CrAl镀层,研究了CrAl微粒在镀层中的含量与搅拌强度、镀液pH值、电流密度及温度的关系,确定最佳工艺参数为:电流密度2.5～4.5A/dm2,pH值4～4.5,温度30℃。采用该工艺制备了较高CrAl含量的复合镀层,并对工艺参数影响复合电沉积的机理进行了简单探讨。     

电沉积工艺对镀锌层的表面形态及电化学性能的影响

采用电沉积技术制备几种电沉积式锌电极,考察镀液中KOH浓度和沉积电流密度对所制得镀锌层的微观形貌与性能的影响规律.结果表明镀锌层的枝晶随着KOH浓度(250～400 g/L)的增加而变得粗大,且其析氢量、腐蚀电位和腐蚀电流密度均呈现先减小而后增加的趋势;随着电流密度(25～100 mA/cm2)的增长,镀锌层由块状结晶向枝晶转变,相应地电极反应活性随之增大,而耐蚀性则随之变差,并发现沉积电流密度为75 mA/cm2时,锌电极的综合性能最好,以200 mA/g充放电循环10周次,其放电容量仍可达504 mA-h/g.解释了主要工艺参数对结晶形态及电极性能影响的原因,并说明适当的KOH浓度和沉积电流密度有利于提高电极的综合性能.     

Cu-W复合电沉积工艺研究

电接触材料要求具有很好的抗电弧烧蚀和抗熔焊性能,但纯铜很难达到该种要求.利用复合电沉积方法,在纯铜表面形成Cu-W复合镀层,使其满足电触头材料的使用性能.重点研究了镀液中W的质量浓度、电流密度、搅拌强度和温度工艺参数对Cu-W电接触材料复合镀层中W微粒沉积量的影响,并且通过正交试验确定了复合电沉积的最优工艺:W的质量浓度为35g/L、电流密度为4A/dm2、搅拌强度为600r/mjn、温度为50℃.     

基于TEA和EDTA·2Na双络合体系的酸性镀铜工艺及镀层特性

锂离子电池用负极集流体铜箔材料目前主要采用电沉积法制备。为制备良好的电解铜箔,采用不同电镀工艺参数,在基于三乙醇胺(TEA)和乙二胺四乙酸二钠(EDTA.2Na)双络合体系的CuSO4/H2SO4溶液中进行镀铜工艺研究。通过线性扫描、循环伏安、SEM和XRD手段对镀液性质、镀层微观形貌和结构进行测定和表征,并进行镀层质量重复性实验。结果表明:选择含P 0.1%的磷铜作为阳极,采取机械搅拌镀液的方式,在CuSO4.5H2O为300 g/L、H2SO4为90 g/L、Cl-为40~80 mg/L、TEA为3.5 g/L和EDTA.2Na为5 g/L中适量添加剂P的镀液中,以电流密度为490 mA/cm2,镀液温度为40~60℃,施镀5~10 min能得到良好镀层;添加剂明显降低循环伏安阴极峰电流,Cu2+的还原速度减慢;添加剂提高镀层表面的结晶细化程度,使晶体颗粒变小,致密性提高,镀层质量变好,整平作用明显,Cu镀层呈现(111)晶面择优取向;镀速可达19.4 mg/min,镀层质量有很好的重现性。     

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。