离子液体对PbO2电极性能的影响

目的 提升PbO2电极寿命以及对酚类废水的电氧化催化活性和选择性。方法 分别添加离子液体1-丁基-3-甲基-咪唑六氟磷酸盐（[BMIM]PF6）和1-乙基-3-甲基-咪唑四氟硼酸盐（[Emim]BF4）至Pb(NO3)2溶液中,用阳极电积法制备了有SnO2+Sb2O3中间层的PbO2电极。通过扫描电镜（SEM）、X射线衍射仪（XRD）、加速寿命实验、线性扫描和循环伏安测试、电氧化降解实验等考察了不同离子液体的电离产物对电极性能的影响,并与采用F-修饰的常规PbO2电极的性能进行了对比。结果 离子液体修饰的PbO2电极晶粒结晶度高,晶面取向发生改变,晶粒大小均一度高,表面平整致密、棱角多,电极有效表面积和活性点增多,且[BMIM]PF6修饰的PbO2优于[Emim]BF4修饰的PbO2。[BMIM]PF6修饰的PbO2和F-修饰的PbO2的加速寿命和电极性能稳定期分别为168.8、162.6 h和101.2、69.8 h,析氧电位分别为1.71 V和1.59 V。循环伏安显示,[BMIM]PF6修饰PbO2氧化峰电位更小,氧化峰电流更大,相同条件下,[BMIM]PF6和F-修饰PbO2对p-NP废水的电氧化降解率和有机碳去除率分别为95.7%、87.1%和85.2%、61.5%,而电解槽槽压分别为3.26 V和3.47 V。结论 离子液体[BMIM]PF6、[Emim]BF4修饰PbO2电极的结晶度、晶粒均一性、致密性增强,电极活性点增多,且由于两种离子液体电离的离子大小不同,导致对电沉积晶粒的空间位阻不同,使得前者强于后者。晶粒形态和组织结构的差异,使得[BMIM]PF6修饰PbO2对酚类废水的电氧化催化活性、选择性和寿命显著增强。     

单/双咪唑环阳离子结构对离子液体薄膜微/纳摩擦学性能的影响*

粘着、摩擦和磨损是影响微/纳机电器件稳定性和寿命的关键因素。利用浸渍-提拉法在硅基底上制备了两种具有单、双咪唑环阳离子结构的离子液体薄膜。采用热重分析仪评价了离子液体的热稳定性。利用原子力显微镜测定了薄膜的表面形貌和纳米摩擦学性能。利用球-盘式摩擦试验机考察了载荷和频率对薄膜的微摩擦学性质的影响。对比分析了基于不同阳离子结构的薄膜的微/纳摩擦学性能。结果表明:两种离子液体薄膜的纳米摩擦力随着原子力针尖扫描频率的增加而增加,且[BMIM]PF6薄膜的摩擦力低于2[BMIM]PF6薄膜。此外,[BMIM]PF6薄膜的微摩擦系数低于2[BMIM]PF6。因此,离子液体的阳离子结构对其作为薄膜的微/纳摩擦学性能有重要影响。     

离子液体[EMIM]Br-AlCl3中恒电流沉积铝

在磁力搅拌下,采用离子液体[EMIM]Br-AlCl3作为电解液并测其电导率,在不锈钢片上利用恒电流法电沉积铝,研究在AlCl3/[EMIM]Br摩尔比为2:1的离子液体中铝的电沉积速率、电流效率和阴极表面形貌的影响因素。采用扫描电子显微镜(SEM)分析沉积铝层的表面形态,采用X射线能谱仪(EDS)测试沉积铝的纯度。结果表明:离子液体[EMIM]Br-AlCl3的电导率随着温度的上升而增大,符合Arrhenius公式。电流密度,温度、搅拌速率和沉积时间均影响铝的沉积速率、电流效率和表面形貌。在电流密度为20 mA/cm2,温度为40℃,搅拌速率为700 r/min,时间为60 min的条件下,所得铝沉积层连续、致密、附着性好、颗粒状且粒径小;电流效率维持在80%以上,阴极铝层纯度达96%,其中少量的氧来自铝的氧化。     

离子液体-水混合介质中合成介孔TiO_2及光催化活性北大核心CSCD

以四氯化钛为钛源,离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[Bmim]PF6）／水为混合溶剂,采用液相水解-沉淀法合成纳米TiO2光催化剂。以苯酚为模型物,考察了TiO2紫外下催化活性。采用XRD、TG／DSC、TEM、FTIR、DRS、低温N2物理吸附．脱附等技术对催化剂的结构进行表征。结果表明,在离子液体／水混合溶剂中合成TiO2的光催化活性较纯水溶剂中合成TiO2的光催化活性高,且在较宽的活化温度范围内（500—700℃）都表现出较高的光催化活性。这-结果可归因于在离子液体／水混合介质中合成的TiO2颗粒小、分散性好、比表面积大（138m^2／g）、吸附性能强。另外,离子液体的存在-定程度上降低了TiO2粒子表面羟基数量及表面酸度,提高了锐钛矿相TiO2向金红石相转变的温度。     

溴代氯铝酸离子液体的微波合成及电沉积铝应用

采用新型微波合成方法制备溴代氯铝酸离子液体,测试其物理化学性能,并将其作为电解质应用于铝的电沉积。通过测定循环伏安曲线、计时电流曲线以及极化曲线探讨铝在2AlCl3/[EMIM]Br离子液体中的电沉积机理。室温下在铜基体上进行铝的恒电位沉积,沉积层形貌以及结构特性分别用SEM、XRD进行表征。结果表明:溴代氯铝酸离子液体的新型微波合成与普通微波合成相比,大大缩短了反应时间,提高了产品性能;铝的电沉积为准可逆的动力学行为,沉积过程非单纯的扩散控制而是复杂的动力学限制步骤;铝在不同电位下的沉积层大致分为3种典型形貌,并对各种形貌产生的原因及特征进行分析。     

201×7树脂对铁氰络合物的吸附动力学

对201×7树脂吸附铁氰化合物的过程进行动力学研究.结果表明,201×7树脂对铁氰化合物有很好的吸附效果.在298 K时,201×7树脂对亚铁氰化络合离子[Fe(CN)6]4-和铁氰化络合离子[Fe(CN)6]3-的静态饱和吸附量分别为8.620和12.072 mg/mL.用均相颗粒扩散模型和收缩核模型对吸附参数进行描述,表明201×7树脂对[Fe(CN)6]3-和[Fe(CN)6]4-的吸附过程均属于液膜扩散控制.由树脂对[Fe(CN)6]4-和[Fe(CN)6]3-的等温吸附线得到Freundlich常数n分别为4.786和6.145;吸附过程中分离系数S和选择系数K均大于1,表明201×7树脂对[Fe(CN)6]4-和[Fe(CN)6]3-两种络合离子都是容易吸附的,而且[Fe(CN)6]3-离子比[Fe(CN)6]4-离子更容易被吸附.     

Q235B低碳钢在不同含水量的布朗斯特酸离子液体中的腐蚀行为

目前有关布朗斯特酸(Brnsted)离子液体腐蚀的报道较少,且含水量对离子液体的酸性影响较大。利用电化学方法研究了Q235B低碳钢在不同含水量的布朗斯特酸离子液体[(CH2)4SO3HMIm][HSO4]中的腐蚀行为,采用扫描电子显微镜(SEM)、能谱仪(EDS)、核磁共振仪分析了Q235B钢电极电化学试验后的表面形貌及元素组成,讨论了其电化学作用机理。结果表明:随着离子液体含水量的增加,碳钢耐腐蚀性降低;此Brnsted酸离子液体同时具有强酸性和低腐蚀性,易循环使用,有望取代具有强腐蚀性的传统酸,成为工业用酸性催化剂。     

Br?nsted酸离子液体对H62黄铜在H_2SO_4溶液中的缓蚀研究北大核心CSCD

研究了两种具有相同有机阳离子、阴离子分别为[HSO4]-(IL1)和[H2PO4]-(IL2)的Br?nsted酸离子液体对H62黄铜在0.5 mol/L H2SO4溶液中的缓蚀作用。其缓蚀行为研究采用静态失重法和电化学测试法,并通过扫描电子显微镜和X射线光电子能谱对黄铜腐蚀表面进行了表面和成分分析。结果表明,这两种离子液体能够在一定的浓度范围内减缓H2SO4溶液对H62黄铜的腐蚀,当两种离子液体浓度达到0.75 mmol/L时,缓蚀效果最好,相同浓度下加入离子液体IL2的缓蚀效果好于IL1,这是由于离子液体均通过静电吸附起到缓蚀作用,其中IL2能在黄铜表面形成难溶的磷酸锌,该腐蚀产物能与离子液体吸附协同作用,形成更牢固致密的保护膜。     

Br?nsted酸离子液体对H62黄铜在H_2SO_4溶液中的缓蚀研究

研究了两种具有相同有机阳离子、阴离子分别为[HSO4]-(IL1)和[H2PO4]-(IL2)的Br?nsted酸离子液体对H62黄铜在0.5 mol/L H2SO4溶液中的缓蚀作用。其缓蚀行为研究采用静态失重法和电化学测试法,并通过扫描电子显微镜和X射线光电子能谱对黄铜腐蚀表面进行了表面和成分分析。结果表明,这两种离子液体能够在一定的浓度范围内减缓H2SO4溶液对H62黄铜的腐蚀,当两种离子液体浓度达到0.75 mmol/L时,缓蚀效果最好,相同浓度下加入离子液体IL2的缓蚀效果好于IL1,这是由于离子液体均通过静电吸附起到缓蚀作用,其中IL2能在黄铜表面形成难溶的磷酸锌,该腐蚀产物能与离子液体吸附协同作用,形成更牢固致密的保护膜。     

甲啶铂在玻碳电极上的电化学行为及其与DNA相互作用研究

采用循环伏安法(CV)和差分脉冲伏安法(DPV),研究了甲啶铂在多壁碳纳米管-离子液体修饰玻碳电极(MWNTs-[ODMIM]PF6/GCE)上的电化学行为,建立了甲啶铂的测定方法;以紫外-可见光谱法和电化学方法相结合,研究了甲啶铂与DNA的嵌插结合作用。结果表明:甲啶铂在MWNTs-[ODMIM]PF6/GCE上有一对氧化还原峰,氧化峰电位Epa与还原峰电位Epc分别为-0.07 V、-0.36 V,峰电位之差为ΔE=0.29 V,Ipa/Ipc=1.11。在优化条件下,甲啶铂的氧化峰电流与其浓度在2.66~532μmol/L范围内成良好的线性关系(r=0.9994),检出限为1.33μmol/L。方法操作简便,准确可靠、灵敏度高,可用于甲啶铂含量的直接测定。     

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。