甲酸盐三价铬电镀工艺的研究

目的解决现有氯化盐体系和硫酸盐体系三价铬电镀存在的问题。方法以甲酸铬为主盐,甲酸铵、尿素和苹果酸为络合剂,通过Hull槽试验和方槽试验,研究铬离子、甲酸铵、尿素、苹果酸的浓度以及镀液pH值、镀液温度、电镀时间等工艺参数对黄铜表面三价铬镀层形貌、沉积速率和光亮范围的影响。结果甲酸铵和尿素分别与Cr3+形成活性络合物,苹果酸具有pH值的缓冲作用。最佳的工艺条件为:Cr3+浓度0.4 mol/L,甲酸铵浓度0.5 mol/L,尿素浓度0.2 mol/L,苹果酸浓度0.05 mol/L,镀液pH值3.5,镀液温度25~30℃。结论该甲酸盐三价铬电镀工艺具有较宽的光亮范围,镀层孔隙率低,光亮致密,沉积速率较高,与铜基体结合良好,结构为混晶态。在室温、电流密度为15 A/dm2的条件下电镀5min,镀铬层厚度即可达到1.78μm,满足装饰性镀铬层的要求。     

三价铬硫酸盐体系电镀Fe-Ni-Cr合金镀层的耐蚀性研究

采用三价铬硫酸盐体系在普通碳素钢基体上电镀Fe-Ni-Cr合金镀层,通过浸泡失重法研究不同工艺条件下制备的镀层在3.5% NaCl溶液中的耐蚀性能,并用电化学分析方法研究了镀层试样的耐蚀机理.结果表明,最佳电镀Fe-Ni-Cr合金工艺为:主盐浓度FeS04·7H2O 15 g/L、NiSO4·6H2O 8 g/L、Cr...     

三价铬电镀铬的工艺研究

通过正交法进行小槽试验和Hull Cell试验,研究了三价铬电镀工艺中的pH值、温度、搅拌、电流密度等工艺条件和参数对镀层的影响.在各不同镀液组成和工艺条件下,充分地分析了镀层的表观形貌,确定了最佳镀液组成和工艺参数:采用了主盐和导电盐均为硫酸盐的全硫酸盐体系的三价铬镀铬;当pH=2～3、Jk=15～45 A/dm2、工作温度=25～45℃时,采取静镀的方法可以得到光亮、致密的合格镀层.     

三价铬镀液组分的存在形式及其对电镀的影响规律

通过理论计算和电镀实验研究镀液核心组分存在形式及其对铬电镀的影响规律。结果表明:络合剂脲或甲酸98%以上是以分子形式与Cr(Ⅲ)离子形成三价铬活性络合物。根据三价铬络合物平衡构象图发现:相比于CrL~(3+),Cr(OH)L~(2+)更高的电化学活性归因于较大的水分子-中心铬离子距离。通过增加三价铬活性络合物浓度,能显著提高铬电镀速率,可高达1.2μm/min;缓冲剂硼酸主要以B(OH)3的形式存在,最佳p H缓冲范围为8~10,而Al~(3+)最佳的p H缓冲范围为3~3.5。加入0.6 mol/L Al~(3+)使铬镀层边缘和中心厚度之比(hcorner/hcenter)从11降低至2;而加入1 mol/L硼酸仅使hcorner/hcenter从5降低至3,Al~(3+)改善镀层均匀性的作用更为明显。     

光亮锡镍合金电沉积新工艺

在研究碱性锡镍合金的电沉积过程中,讨论了镀液中各成分的含量、电镀工艺条件的改变及添加剂对锡镍合金镀层成分和外观的影响规律。获得了内应力小,同基体结合力好,表面光亮、平整致密,具有高耐蚀性的合金镀层。优化工艺为:SnCl215g/L,NiSO4.6H2O 35g/L,K4P2O7.3H2O 260g/L,NH4Cl 12g/L,糖精2g/L,十二烷基磺酸钠2.5g/L,对苯二酚1.5g/L,pH 8.5,Dk1.5A/dm2,温度30℃。     

快速化学镀 Ni-Zn-P 合金工艺及镀层性能

目的确定快速化学镀Ni-Zn-P合金的工艺。方法通过一系列实验,研究主盐含量、pH值、温度、时间等对镀层沉积速度及镀层锌镍比的影响,确定最优工艺条件。借助SEM,EDS,XRD及电化学方法分析镀层微观形貌、成分及耐蚀性。结果在ZnSO4·7H2O8 g/L,NiSO4·6H2O 35 g/L,NaH2PO2·H2O20 g/L,NH4Cl 50 g/L,C6H5Na3O7·2H2O 70 g/L,稳定剂1.5 mg/L,p H=9.0,温度90~95℃的条件下,化学镀Ni-Zn-P合金沉积速度为5~6μm/h,镀层中Zn质量分数为8%~10%,P质量分数为6%左右,Ni质量分数为80%~85%。Zn的存在使Ni呈现出晶态结构,在XRD谱图上2θ=45°及2θ=52°位置分别出现了Ni(111),Ni(200)衍射峰。施镀时间不会影响镀层成分,但会影响镀层耐蚀性。施镀1.5 h时,镀层厚度约为9~10μm,其耐蚀性略好于相同厚度的Ni-P镀层。结论 Ni-Zn-P化学镀沉积速度较快,8%~10%的Zn使镀层中Ni呈晶态结构,且改善了镀层耐蚀性。     

硫酸盐电镀三价铬镀层性能研究

为对硫酸盐体系三价铬镀层性能进行更深入的了解,分析了电镀时间对镀层厚度、表面形貌和镀层耐蚀性的影响.采用X射线荧光光谱仪、体视显微系统对镀层厚度和形貌进行了测试;通过CASS试验、Tafel曲线和EIS曲线测试,对采用不同电镀时间制备的三价铬镀层及六价铬镀层的耐蚀性进行了分析.试验结果显示:三价铬镀层厚度基本随电镀时间的增加而线性增加;电镀时间达到10min时,镀层表面形貌由微孔变为微裂纹状,镀层耐蚀性最好;硫酸盐体系三价铬镀层的耐蚀性与六价铬镀层的耐蚀性相当.可见,硫酸盐体系三价铬镀层具有优良的耐蚀性.     

Cr-Al2O3纳米复合电沉积的研究

采用单因素实验方法探讨了电流密度、温度、pH值、搅拌速度对电沉积Cr-Al2O3纳米复合镀的影响;并用L9(34)正交实验方法,确定了主络合剂、辅助络合剂、分散剂、AlCl3.6H2O对纳米复合镀层外观、厚度以及纳米氧化铝含量的影响,确定了最佳镀液配方,并利用扫描电镜、能谱仪和硬度测试仪测试了所得镀层的形貌和性能。结果表明:在最佳工艺条件下,以主络合剂18.9g/L,辅助络合剂3.85g/L,分散剂质量分数2%,结晶氯化铝12g/L所得的镀层厚度可达到13.93μm,纳米氧化铝的质量分数平均可达到10.90%,镀层的显微硬度可达到867.9HV。     

掺杂钨丝电沉积铬的工艺研究

为了研究掺杂钨丝（真空镀铬加热元件）表面电解沉积一定厚度（≥100μm）金属铬的工艺,详细考察了不同温度、电流密度、沉积时间等对镀层的影响,并对镀层进行了性能测试。结果表明,最佳工艺条件为：铬酐150—180μg／L,硫酸1．5～1．8g/L,稀土（La^3＋）添加剂0．5-1．5#L,温度为55℃,电流密度为8～10A／dm^2,电镀时间3h。此工艺条件下所得镀层光亮,色泽好,厚度可达100μm,且镀层耐蚀性好,结合力高。     

Cr-α-Al_2O_3复合电沉积工艺

在三价铬电沉积工艺基础上制备了Cr-α-Al2O3复合镀层。探讨了镀液中Al2O3粒子浓度、搅拌速率、温度等对复合镀层厚度、微粒复合量的影响,并对镀层的微观形貌、结合力、耐腐蚀性能等进行了检测。结果表明:复合镀层与基体结合良好,随Al2O3颗粒浓度的增加,复合镀层厚度及复合量都是呈先增后减的规律;搅拌速率对镀层厚度影响较小,复合量存在极值,转速达220 r/min时,颗粒复合量最多;温度的上升使得镀层厚度及复合量呈下降趋势。与单金属铬镀层相比,Cr-α-Al2O3复合镀层的裂纹明显细化。在耐腐蚀测试中,Cr-α-Al2O3复合镀层在NaCl介质中耐蚀性最好,在NaHCO3中次之,在H2SO4中最差。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.