模拟铁器文物恒电位脱氯控制电位的研究

采用模拟闭塞电池恒电位极化法研究了模拟铁器文物在碱性溶液脱氯过程中外电位对闭塞区内电化学状态的影响。实验结果表明，外电位对闭塞区内电极电位和闭塞区内外电极间电偶电流影响很大，氯离子迁出率也与外电位密切相关。恒电位脱氯控制电位选择范围的上限值对应于临界电位，下限值应保证闭塞区内电极电位正于析氢电位。     

铸铁文物在碱性溶液中的电化学脱氯研究

采用模拟闭塞电池恒电流法和恒电位法研究在碱性溶液中阴极极化对模拟铸铁文物局部腐蚀闭塞区内溶液化学和电化学状态的影响以及电化学脱氯的效果。试验结果表明，对试样进行恒电流或恒电位阴极极化，闭塞区内溶液的pH值随着阴极极化时间的延长而升高；氯离子向闭塞区外迁移，迁移率随阴极极化时间的延长而增高。由于Cl^-的迁出及外部OH^-的迁入，闭塞区内的腐蚀受到抑制。阴极极化能加速闭塞区内Cl^-的迁出，比铸铁文物通常采用的碱性溶液浸泡脱氯法更为有效，是一种快速的电化学脱氯方法。     

铁质文物电化学脱盐材料的研究

采用电化学极化法在铸铁表面制备出锈层以模拟带锈的铁质文物,对试样用恒电流极化法进行脱氯处理,在脱氯过程中采用不同材质、不同形状、不同分布方式的辅助电极,比较脱氯效果表明,用笼状低碳钢网做辅助阳极,经过48 h的恒电流脱氯,试样中氯离子迁出率可达70.10%,氯的含量由5.26 mass%下降到0.32 mass%.综合考虑脱氯辅助阳极材料成本、可操作性以及脱氯效果,低碳钢网作为辅助阳极综合性能较高.     

碱性溶液中阴极极化对模拟铸铁文物局部腐蚀闭塞区化学和电化学状态的影响

采用模拟闭塞电池恒电流法研究在碱性溶液中阴极极化对模拟铸铁文物局部腐蚀闭塞区内溶液化学和电化学状态的影响.结果表明：对试样通入阴极电流后,闭塞区内溶液的pH值随着通电时间的延长及阴极电流密度的增大而升高;氯离子向闭塞区外迁移,迁移率和迁移速率随时间的延长和电流密度的增大而增高.由于Cl^-的迁出及外部OH-的迁入,闭塞区内的腐蚀受到抑制.通阴极电流能加速闭塞区内Cl^-的迁出,比铸铁文物通常采用的碱性溶液浸泡脱氯法更为有效,是一种快速的电化学脱氯方法.     

利用原位合成吸水性树脂延缓砂浆中钢筋锈蚀研究

利用吸水性树脂吸水膨胀、密实孔隙、截断侵蚀性介质传输路径的新方法,研究了砂浆经原位合成吸水性树脂处理前后其内部预埋钢筋的腐蚀行为.实验以氯离子渗透系数、氯盐加速腐蚀条件下钢筋腐蚀电位及极化电流密度的动态变化评定了该方法的可行性.结果表明:砂浆经原位合成吸水性树脂表层处理后,氯离子渗透系数和钢筋腐蚀速率明显减小.     

Ag/AgCl氯离子选择性探针电极的制备及其性能表征

将银针在0.1 mol/L HCl电解液中采用恒电流法进行氯化处理,制备Ag/AgCl氯离子选择性电极。采用扫描电镜、能谱与XRD测试,考察氯化前后银表面厚度与表面物质元素的变化;通过对电极对氯离子响应时间的测量,考察电极电位对氯离子的敏感性;通过对响应斜率的测量,考察电极电位与浓度的相关关系。结果表明,在银表面经氯化处理后得物质是AgCl,该电极对氯离子的响应迅速且电位稳定,电极电位与氯离子的浓度呈线性相关关系。制备的选择性电极能在较大的pH值范围内使用,且其他离子对该电极的电位影响较小。     

黄铜脱锌腐蚀的恒电位试验法的研究

本文从电化学原理出发,对一种新的脱锌试验方法——恒电位法进行了比较详细的研究。结果表明:恒电位法是一种可靠的、有代表性的层式脱锌试验方法;与常用的静态和动态脱锌试验法相比,其突出优点是试验工作效率高、电化学条件稳定而易控制以及受温度的影响小。文中给出了常用黄铜的恒电位脱锌试验控制条件。     

矿物掺合料对钢筋氯盐腐蚀行为的影响及其作用机理

用水泥提取液模拟混凝土孔隙液,用自腐蚀电位、动电位极化和电化学阻抗技术,研究单掺粉煤灰或矿粉、复掺粉煤灰和矿粉对混凝土中钢筋氯盐腐蚀行为的影响.结果表明,粉煤灰和矿粉均能有效降低钢筋受氯离子腐蚀的风险,减小腐蚀速率,并能不同程度地提高钢筋腐蚀的临界氯离子浓度.抑制氯离子腐蚀能力由强到弱依次为:矿粉>矿粉+粉煤灰>粉煤灰>水泥.且随氯离子浓度的增大,矿粉和粉煤灰的阻锈效率会有不同程度的下降.用矿粉和粉煤灰按适当比例复掺的方法来对抗氯离子腐蚀不仅经济,而且有不错的阻锈效果.     

缓蚀剂阳极脱附现象的研究：Ⅲ.缓蚀剂阳极脱附机制

用电化学方法研究了缓蚀剂发生阳极脱附的机制。实验中发现缓蚀复盖度在低于脱附电位时保持不变，达到脱附电位后迅速降低，脱附电位则随缓蚀抑制能力的增强，浓度增加和氯离子的存在而正移，然而，缓蚀剂层阳极溶解的阻力在脱电位之前就逐渐降低。依据这些结果提出离了化金属粒子对吸附层的冲击导致缓蚀发生阳极脱附，而大量缓蚀剂脱附则发生在达到脱附电位后，缓蚀剂再吸附修补附层速度低于脱附速度时。     

不锈钢孔蚀诱导时间的统计研究

用恒电位法测定了18-8不锈钢在中性氯离子溶液中孔蚀的诱导时间。实验数据分析表明,诱导时间的倒数的随机变化规律服从对数正态分布。同样,诱导时间亦服从对数正态分布。并讨论氯离子浓度对分布参数的影响。     

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。