硅钨酸修饰多晶铂电极及其电催化性能

通过循环伏安扫描制备了硅钨酸修饰多晶铂电极，在电极制备过程中发现，SiW12在Pt电极表面的氢区发生了氧化-还原反应，而在氧区使电极表面含氧粒子的吸附增加。通过循环伏安和恒电位I-t曲线研究了该修饰电极在硫酸溶液中的电化学行为和对甲醇氧化的电催化作用。研究结果表明：硅钨酸修饰多晶铂电极提高了甲醇氧化的催化活性和抗CO中毒性。     

钽在硫酸氢根离子无水乙醇溶液中的电化学行为

采用动电位极化、循环伏安、电流暂态和阻抗等技术研究钽在四丁基硫酸氢铵（TBAHS）乙醇溶液中的电化学行为。研究结果表明：循环伏安曲线中没有活化-钝化转变,阳极电流密度随溶液温度、TBAHS浓度、电位扫描速率和水含量增加而增加;表观活化能为43.389kJ/mol,溶解过程为扩散控制。恒电位测试结果表明,当电位较低时,电流密度逐渐降至一稳定值;当电位高于某一值时,电流密度最初下降至一最小值然后逐渐增加。钝化膜电阻随电位升高而减小,当电位高于2.0V时,出现感抗弧。     

Sb(Ⅲ)在碱性木糖醇溶液中的阴极电沉积(英文)

运用循环伏安法、线性电位扫描法研究木糖醇在碱性溶液(含锑)中的电化学稳定性及锑在木糖醇碱性溶液中的沉积动力学参数;采用计时电流法研究锑在不锈钢阴极上的电化学成核机理。循环伏安测试结果表明,木糖醇在碱性溶液中的稳定性较好,在-1.20V～+0.60V(vsHg/HgO)范围内无氧化还原反应发生,在电位负于-1.70V(vs.Hg/HgO)时木糖醇在锑电极上可能发生分解。在该体系中,锑在阴极上的沉积经历了不可逆电结晶过程。根据线性电势扫描结果,锑沉积的活化能、表观传递系数、交换电流密度等动力学参数分别为46.33kJ/mol、0.64和4.40×10-6A/m2。计时电流法实验结果表明,锑在碱性木糖醇溶液中的成核机理符合扩散控制下的三维连续成核模型,外加电位对晶体生长速率和恒定电位下的饱和晶核密度有显著影响。通过分析恒电位阶跃曲线,求出锑离子在该体系中的扩散系数为1.53×10-6cm2/s。     

TA2纯钛阳极氧化膜的制备和电化学分析

10%H2SO4溶液作为电解液,采用恒电位的方式在纯钛的表面成功制备出阳极氧化膜。采用电化学的方法在3.5%Na Cl溶液中研究了低电位下阳极氧化膜的I-t曲线、Tafel极化曲线、电化学阻抗谱以及Mott-Schottky曲线。结果表明:在确定的工艺参数下,可获得色彩丰富、表面平整、光滑的阳极氧化膜。I-t曲线显示氧化膜的形成是动态生长和溶解的过程;Tafel曲线和阻抗谱显示阳极氧化后的TA2纯钛具有更好的耐蚀性,且阳极氧化电压越高,耐蚀性越好;Mott-Schottky显示阳极氧化膜为n型半导体,且施主浓度随电位升高而减小,耐蚀性随之提高。     

杂多酸修饰碳载铂钌电极的电催化性能

利用化学还原法合成了PtRu/C催化剂,并通过XRD测试表明铂钌形成了合金相.分别采用磷钼酸和磷钨酸对PtRu/C电极进行了修饰,并用循环伏安曲线和不同电位下的恒电位I-t曲线测试了它们的性能.结果发现:磷钼酸修饰的PtRu/C电极氧化甲醇的电催化活性更高.     

冰晶石熔盐中阳极效应时石墨阳极的电化学行为(英文)

在1000℃下采用循环伏安法研究石墨阳极在冰晶石氧化铝熔盐中的阳极电化学行为。讨论了循环伏安曲线中较高的电流峰。结果表明,在高电位条件下,一种含氧氟络合阴离子中的氟与碳阳极反应,且在阳极表面生成一层高电阻的CF膜。在含0.5%氧化铝的电解质中,石墨电极钝化电位为3.28V,并随着氧化铝含量的增加而增大。这一现象表明,在冰晶石-氧化铝熔盐体系中氧化铝含量对阳极过程起着主导作用。     

低温下YL15对黄铜矿和斑铜矿的协同浸出及电化学研究

采用生物浸出和电化学测试,研究低温10℃下AcidithiobacillusferrivoransYL15对黄铜矿和斑铜矿的协同浸出过程,结合不同的电化学测试手段探究其电化学溶解和表面钝化行为。结果表明:不同矿物体系的生物浸出和电化学行为存在极大差异。协同浸出组的浸出率最高,达到了48.4%,斑铜矿的次之,且两者都远高于黄铜矿的16.4%。斑铜矿的加入降低了氧化还原电位并维持到一个适宜的范围(400~420 mV),加快了矿物的氧化。另外,通过电化学测试,发现协同浸出组的电位降低、电流升高和阻抗减小、氧化速率大幅提高。     

斑铜矿在50℃浸出过程中的铜物相转化（英文）

研究斑铜矿在50°C的混合中等嗜热微生物浸出。通过XRD和XPS表征在斑铜矿浸出过程中形成的中间产物,并利用φh-p H图和循环伏安曲线进一步分析斑铜矿浸出过程中铜状态的转化。结果表明:较高的溶液(氧化还原)电位更有利于斑铜矿的浸出;在斑铜矿的浸出过程中可能形成方黄铜矿、铜蓝、黄铜矿以及二硫化物和多硫化物等中间产物;Cu 2p光电子能谱显示,斑铜矿和中间产物中铜的价态均为+1。斑铜矿和黄铜矿之间可以相互转化,并且两者都可以进一步转化为铜蓝和/或辉铜矿。     

乙硫氮在铁闪锌矿表面吸附的电化学行为及机理

采用光谱分析、循环伏安及恒电位阶跃法,研究了乙硫氮(NaD)在铁闪锌矿表面吸附的电化学行为及机理,该机理与浮选电化学的混合电位模型并不一致.在酸性条件下,当电位为0～200 mV时,乙硫氮在铁闪锌矿表面电化学吸附形成双乙硫氮(D2);当电位为410 mV时,乙硫氮与矿物发生电化学反应形成ZnD2和S°,并产生钝化,且表面疏水性强;当电位大于600 mV,电极过程由自腐蚀反应控制.在中性和碱性条件下,铁闪锌矿表面的电极过程主要由自腐蚀阳极溶解控制.随着pH值的增大,表面中间态分别为Fe(OH)D2、Fe(OH)2D和Zn(OH)D,并随电位增大进一步氧化成Zn(OH)2、Fe(OH)3和D2,且矿物表面亲水性强.在开路电位条件下,铁闪锌矿表面存在双乙硫氮和乙硫氮金属盐,但不能有效地附着在电极表面.     

电位对天然黄铜矿表面膜层性质的影响

采用循环伏安（CV）、扫描电子显微镜（SEM）和电化学阻抗谱（EIS）研究黄铜矿在含有5×10-4mol/L乙黄药溶液中的电化学行为以及电位对黄铜矿表面膜层成分和性质的影响。结果表明：在开路电位（OCP）下,天然黄铜矿表面发生黄药阴离子的吸附过程;在阳极电位范围-0.11～0.2V内,主要发生黄药阴离子氧化形成疏水双黄药膜层的电化学过程。形成的双黄药膜层在电位为0V时具有较高覆盖度和较大的厚度,随着电位的增加表面双黄药膜层的覆盖度和厚度减小。当电位高于0.2V时,黄铜矿表面发生以自身活化溶解为主的电化学过程,黄铜矿表面由双黄药膜层转化成为大量具有多孔和疏松结构的含有Cu（Ⅱ）和Fe（Ⅲ）的氧化物。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.