人工模拟海洋大气环境下Sn-0.7Cu无铅焊料的点蚀行为及微量Ga的影响

通过人工海水的盐雾干-湿实验模拟海洋大气环境,研究了Sn-0.7Cu和Sn-0.7Cu-0.01Ga合金的腐蚀行为.采用SEM和XPS分析了合金表面腐蚀形貌及腐蚀产物成分,采用XRD分析了腐蚀产物的结构.结果表明:Sn-0.7Cu合金腐蚀初期发生明显的点蚀,点蚀易于在富Cu区萌生,且以触须状向外扩展;腐蚀后期腐蚀产物分层,龟裂且易于剥落,此时腐蚀产物不具有保护性.XRD分析表明.腐蚀产物主要为非晶态Sn的氧化物,同时有少量的SnCl_2·2H_2O;微量元素Ga能显著提高Sn-0.7Cu合金的抗盐雾腐蚀性能.XPS分析表明,微量元素Ga在表面存在明显的富集行为,并形成一种致密的保护性氧化膜,它是提高Sn-0.7Cu合金抗盐雾腐蚀性能的主要原因.     

Cu-Zn-Ni-Sn仿金合金在人工海水和人工汗液中的腐蚀行为EI北大核心CSCD

采用色差测试、电化学测试、静态腐蚀测试、扫描电镜分析、电化学阻抗测试和X射线光电子能谱分析等方法,研究仿金Cu-Zn-Ni-Sn合金在人工海水和人工汗液中的腐蚀行为。合金在人工海水腐蚀初期的腐蚀产物层主要为较为致密的Cu2O和具有良好耐腐蚀性能的Zn O、Zn5(CO3)2(OH)6和Zn5(OH)8Cl2·H2O等氧化产物,该氧化膜两侧界面的传质过程是腐蚀反应发生的决速步骤。在人工汗液中腐蚀初期的主要腐蚀产物主要为疏松的Cu O和不稳定的Sn O,使其腐蚀产物膜疏松、易剥落。在人工汗液的腐蚀过程中,早期形成的腐蚀产物层会开裂,而裂纹末端界面的固相扩散决定了腐蚀反应的速率。     

青铜器加速腐蚀的多孔氧电极研究

用具有适当空隙的电镀Cu-Sn-Pb三元合金作为青铜器模拟试片.应用腐蚀膏试验和微电极测试,研究了氯化亚铜(CuCl)、碱式氯化铜［Cu2Cl(OH)3］和碱式碳酸铜［Cu2(OH)2CO3］等腐蚀产物对氧的去极化反应的影响.以上述铜盐为活性物质制备出多孔氧电极,与青铜试片在3％NaCl溶液中组成腐蚀原电池,进行了阴极极化曲线测试,并进行以CuCl为活性物质的氧电极的恒电流放电和恒电阻放电测试.结果表明CuCl使试片的腐蚀速度高出其它二价铜盐两个数量级,对氧的去极化反应催化活性最高,氧电极的放电性能稳定并且模拟了被称为“粉状锈”主要成分的Cu2Cl(OH)3的生成过程 .提出了加速青铜器小孔腐蚀的多孔氧电极机理.     

青铜制品的腐蚀行为研究

通过模拟闭塞电池实验对青铜制品表面局部腐蚀过程进行了研究。结果表明,合金元素选择性腐蚀和溶解速度顺序均为铅、铜、锡。随着腐蚀时间延长,腐蚀产物起初为Cu Cl和少量Cu2O,然后产生Cu Cl、Cu2O和少量Cu2Cl(OH)3、Cu4SO4(OH)6;腐蚀产物呈层状,由内至外依次为Cu Cl、Cu Cl及Cu2O、Cu4SO4(OH)6H2O。     

LC4铝合金在格尔木盐湖大气环境中的腐蚀行为

通过在我国西北格尔木典型大气环境进行大气暴露实验,测定LC4铝合金在该地区的腐蚀率;利用扫描电镜(SEM)、能量色散X射线谱(EDX)、电子探针(EPMA)、红外光谱(FTIR)和X射线衍射仪(XRD)观察分析LC4铝合金腐蚀表面形貌、元素分布和腐蚀产物结构。结果表明:LC4铝合金的腐蚀以点蚀为主要特征,比其在非盐湖大气环境中的腐蚀严重,朝地面的腐蚀比朝天面严重,腐蚀产物层中含有大量的氧和铝,较多的氯和硫;主要腐蚀产物为Al2O3,Al2O3.2SiO2.2H2O和Al2Cl6.6H2O;含氯和硫的盐参与铝合金的大气腐蚀过程,并起到促进腐蚀的作用。     

Fe-14Cr-Mn合金在不同温度熔融共晶NaCl-MgCl_2中腐蚀行为及机理研究（英文）

熔融共晶NaCl-MgCl_2作为太阳能中高温相变储热介质,运行状态下其温度常在熔点附近波动。但不同温度下该熔融盐对金属容器材料腐蚀行为不清楚。以Fe-14Cr-Mn合金为例,采用浸盐法研究了718、768和818 K共晶熔融NaCl-MgCl_2对该合金的腐蚀行为,探讨了腐蚀机理。结果表明:腐蚀速率随温度增加略微增加,3种温度下试样腐蚀动力学曲线服从线性规律(斜率k≈–4.806×10~(-4))。腐蚀初期,试样表面形成泡状腐蚀产物,腐蚀80 h后形成腐蚀坑洞,主要是Fe、Fe-Cr和MgO,也检测到含微量Fe和Ni的Mg-Fe-Ni的氧化物。腐蚀机理主要是MgCl_2吸潮后以H2O形式引入的氧原子和溶解在熔融盐中的微量氧作为阴极去极化剂,合金元素Cr和Mn与Cl-反应生成氯化物,氯化物吸附水分子,形成具有低熔点的含水氯化物(如CrCl3·6(H_2O)和MnCl_2·n(H_2O))逃逸腐蚀体系。另外,在熔盐表面形成了由MgCl_2·(H2O)6,NaCl和MgO组成的盐壳,而在熔融盐内部,NaCl与NaMgCl_3共存。本研究为研发耐熔融NaCl-MgCl_2腐蚀的新合金奠定了基础。     

H62黄铜/TC4钛合金焊接件腐蚀行为研究

采用真空扩散焊接进行H62黄铜与TC4钛合金的焊接,并使用3.5%(质量分数) NaCl溶液对焊接件进行全浸实验。利用SEM及EDS对焊缝两侧的微观形貌及元素分布进行分析,并分析距离焊缝不同距离的区域内,H62黄铜的微观腐蚀形貌的差异;利用扫描Kelvin探针测试焊缝区及其两侧基底合金的表面电位随浸泡时间的变化,分析焊接件的电偶腐蚀规律;利用XPS分析焊接后的H62黄铜与TC4钛合金区域的化学成分,并分析其腐蚀机理。结果表明,由真空扩散焊连接的H62黄铜及TC4钛合金焊缝间距约为25～30μm;浸泡实验初期H62黄铜电位略高于TC4钛合金的,但是随着浸泡实验时间延长,H62黄铜的表面电位开始逐渐下降,后期(4 h)表面电位开始低于钛合金的;同时,距离TC4钛合金较近区域的H62黄铜腐蚀较焊缝远处的更严重;H62黄铜浸泡实验后的腐蚀产物主要包括CuO,Cu_2O,CuCl,CuCl_2和Cu(OH)_2,而TC4钛合金表面主要为含有TiO_2和Ti_2O_3的氧化膜。说明浸泡在3.5%NaCl溶液中的H62黄铜/TC4钛合金焊接试样存在电偶腐蚀倾向,H62黄铜作为阳极被加速腐蚀,TC4钛合金作为阴极被保护,阴极和阳极区域间的电偶对距离作用越长,腐蚀程度越轻。     

凝露状态下SO2对A3钢腐蚀机理的影响

采用红外光谱、电化学交流阻抗和扫描电镜等方法研究了大气中对金属腐蚀性最强的污染物SO2在凝露状态下对A3钢的腐蚀作用规律.结果表明,A3钢在加SO2试验环境中腐蚀失重随试验时间延长呈正指数变化规律;试样表面呈龟裂状腐蚀形貌,红外光谱的分析结果显示出腐蚀产物为FeSO4@7H2O、Fe2(SO4)3@9H2O和γ-FeOOH,还含有δ-FeOOH及少量的Fe(OH)2和Fe3O4.A3钢在未加SO2试验环境中腐蚀失重随时间呈直线变化规律;腐蚀产物主要为Fe2O3和γ-FeOOH;试样表面未形成连续的腐蚀产物膜.     

青铜文物表面腐蚀产物的组成及深度分布研究

青铜在模拟环境介质中的循环伏安实验及XRD测试结果表明,氧化过程主要为生成有害锈CuCl的过程,还原过程主要为CuCl还原成纯铜晶粒的过程,并且反应电流较大,对青铜基体的破坏性较大.运用高性能二次离子质谱(SIMS)观测到不同腐蚀电位下青铜表面腐蚀产物中均含有Cu、Sn、Cl、O、C、S元素,阴离子相对含量由大到小为Cl、O、C、S;腐蚀产物层由表及里Cu/Sn值始终小于合金中Cu/Sn,并且Cu离子含量基本不变,Sn离子含量有起伏,Cl、O离子含量有所下降.     

Sn-9Zn共晶型无铅焊料的大气腐蚀行为

    采用户外大气暴露和人工模拟溶液的方法.研究了Sn-9Zn合金在大气环境和腐蚀性溶液中的腐蚀行为.结果表明,在户外大气暴露12天,合金表面已发生明显的腐蚀;腐蚀产物的微观形貌主要有刺球状和针状两种;除Zn与Sn以外,腐蚀产物中还含有大量的O,分析认为可能是一种Sn-Zn的氢氧化物;在实验条件范围内,合金在腐蚀溶液中腐蚀速度相对较快,在15天内平均腐蚀质量损失达到0.20 mg/dm²～0.25 mg/dm²,表面腐蚀速度与腐蚀溶液中盐的浓度关系不大.     

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).     

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.     

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.     

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。