镀液配方及化学镀工艺对Ni-P合金镀层性能影响

通过Ni-P合金镀层硬度、耐蚀性与表面含磷量的关系,分析了镀液镍次比、pH值、络合剂、缓冲剂以及施镀温度、施镀时间、时效温度对Ni-P合金化学镀层含磷量的影响,探讨了提高镀层表面硬度、耐磨性、耐蚀性的方法.     

石墨化学镀Ni—P合金的结构及耐蚀性研究

采用扫描电子显微镜、X射线衍射及阳极极化曲线测定等方法,对石墨化学镀Ni-P合金的组织结构及耐蚀性进行了研究.结果表明,该镀层在磷含量大于8%时为非晶态结构;加热到300℃时转变为晶态结构;其表面形貌与普通碳钢Ni-P合金层的表面形貌相同.在不同pH值且含有级离子的介质中均有钝化现象,镀层结合力极强.因此该镀层具有很好的耐蚀性.     

化学镀镍层的物理和化学性能与磷含量的关系

研究了镀态和热处理后的镀层度和耐性与磷含量的关系，结果表明，化学镀镍层的牧师和性能与其含磷量有明显关系，镀态低磷镀层的硬度高于高磷镀层的硬度。高磷镀层的耐蚀性优于低磷镀层，镀态的耐蚀性优于热处理态。     

硅片表面制备Ni68Co24P8化学镀层及其性能研究

在p型100单晶硅表面制备了Ni68Co24P8化学镀层,分析了镀层的显微结构、耐蚀性及磁学性质。结果表明:Ni68Co24P8镀层为非晶结构,表面均匀分布着直径约为0.5～4.2μm的球状团簇;在10.0%NaOH溶液和3.5%NaCl溶液中,镀层表现出活化—钝化—过钝化的腐蚀行为,而在1.0%H2SO4溶液中,镀层表面无法形成钝化膜,耐蚀性大幅下降;室温下,Ni68Co24P8镀层呈典型的软磁特征,饱和磁化强度为33.4A.m2/kg。     

铸铁件的Ni-P合金化学镀层性能研究

在QT600-3、HT200基体上制备了Ni-P合金化学镀层,分析了该镀层含磷量、表面形貌、后处理(封孔)对镀层耐蚀性的影响,热处理对镀层表面硬度的影响,活化处理、热处理对镀层结合力的影响规律.对镀层的物理、化学性能检测结果表明,获得的镀层性能良好.       

Zn-Fe-SiO2复合镀层的耐蚀性研究

采用电沉积的方法，制备了Zn-Fe-SiO2复合镀层，对比了该镀层与Zn-Fe合金镀层及Zn镀层的耐蚀性，并研究了镀层成分对镀层耐蚀性的影响，发现该复合镀层无需钝化处理即具有很高的耐蚀性，而且镀层在酸性溶液中的耐蚀性随着镀层中Fe含量的增大而提高，在中性溶液中的耐蚀性随着镀层中SiO2含量的增大而提高.      

Ni-P梯度镀层在3.5%氯化钠溶液中的耐蚀性

碳钢表面化学镀Ni-P镀层内应力大、结合强度低从而导致其耐蚀性降低,限制了其在某些重要零部件的应用。采用化学镀技术在45~#钢表面制备了磷含量由低到高的Ni-P梯度镀层,并采用横截面金相法测量了镀层的厚度,利用线性极化曲线和浸泡试验研究比较了该梯度镀层与三种均质镀层的耐蚀性。结果显示,Ni-P梯度镀层在3.5%NaCl溶液中的耐蚀性好于均质的低磷、中磷和高磷镀层,其耐点蚀性能明显优于均质镀层。     

添加剂对AZ91D镁合金化学镀镍磷耐蚀性的影响研究

采用常温碱性超声波清洗、酸洗和活化的前处理工艺在AZ91D镁合金表面化学镀镍,研究了辅助络合剂氨基乙酸和加速剂巯基乙酸对镀层耐蚀性的影响。结果表明:镀层表面由Ni-P固溶体组成,呈现尖锐的晶态峰,磷原子与镍原子形成置换固溶体,表面平整致密,无明显缺陷。氨基乙酸含量对镀层耐蚀性和腐蚀速率影响不大,随着巯基乙酸含量的增加,镀层腐蚀电位先升高后降低,腐蚀速率整体比镁合金基体慢,镀层总体呈现钝化趋势,在4 g/L时腐蚀电位最高。     

温度对AZ91D镁合金化学镀镍层结构和耐蚀性能的影响

针对AZ91D镁合金,采用酸性化学镀液体系进行化学镀镍,研究了化学镀温度对镀层表面形貌和截面结构的影响,讨论了不同镀液温度下表面形貌的演变过程及镀层的耐蚀性能。结果表明:温度对膜层结构和成分影响较大,温度越高,镀层表面越均匀、致密,且相同时间内获得的镀层厚度越厚,但研究中超过90℃时镀层表面及膜基界面均出现了较多孔洞;80℃时镀层含磷量达到峰值。由于温度影响了镀层结构和成分,最终导致了镀层耐蚀性的差异,80℃时镀层耐蚀性最好。     

温度对AZ91D镁合金化学镀镍层结构和耐蚀性能的影响

针对AZ91D镁合金,采用酸性化学镀液体系进行化学镀镍,研究了化学镀温度对镀层表面形貌和截面结构的影响,讨论了不同镀液温度下表面形貌的演变过程及镀层的耐蚀性能。结果表明:温度对膜层结构和成分影响较大,温度越高,镀层表面越均匀、致密,且相同时间内获得的镀层厚度越厚,但研究中超过90℃时镀层表面及膜基界面均出现了较多孔洞;80℃时镀层含磷量达到峰值。由于温度影响了镀层结构和成分,最终导致了镀层耐蚀性的差异,80℃时镀层耐蚀性最好。     

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。