酸性介质中Pt电极上α-丙氨酸吸附和氧化的EQCM研究

应用电化学循环伏安和石英晶体微天平(EQCM)方法研究了0．1mol/L H2SO4溶液中α—丙氨酸在Pt电极上的吸附和氧化过程。从电极表面质量变化的结果分析，可认为0．1mol/L H2SO4溶液中正向电位扫描时氢区表面质量的增加是由于水分于取代Had引起的，而双电层区的质量增加则是由于H2O的吸附模式逐渐由氢端吸附转向氧端吸附所致。根据频率变化和电量数据，进一步推算出酸性溶液中α—丙氨酸在Pt电极表面只发生弱吸附。H2O和α—丙氨酸阴离子都可以取代氢吸附在电极表面，吸附物种抑制了部分氢的吸附、脱附，并影响电极表面质量的改变量，而吸附态α—丙氨破在高电位氧化时会消耗Pt表面的氧，本文结果可为认识α—丙氨酸在Pt电极表面过程提供定量的新数据。     

5083 铝合金环氧涂层盐水浸泡失效研究

目的研究铝合金基体上环氧涂层在盐水浸泡环境中的电化学阻抗谱变化规律,揭示涂层失效的原因和机制。方法采用电化学阻抗谱技术、红外测试、扫描电镜及能谱分析等方法,研究涂覆在5083铝合金基体上的环氧涂层在盐水浸泡过程中的裂化过程和失效机制。结果在3.5%(质量分数)Na Cl溶液的连续浸泡下,涂层电阻明显下降、电容明显增大,相应的涂层孔隙率和吸水体积百分数均逐渐增加;长期浸泡后,涂层孔隙率和吸水体积百分数均趋于稳定。随着浸泡时间的增加,涂层表面孔洞等缺陷增多,保护作用减弱;涂层内氧元素含量逐渐增加,碳元素含量逐渐减小;涂层内有羟基生成和C—O键的断裂发生。结论环氧涂层中环氧官能基团在电解质溶液中发生水解,水解形成羟基和氨基等亲水基团以及涂层中存在的孔洞等缺陷,进一步促进电解液的渗透,加速涂层的劣化。金属基体表面腐蚀反应会促进涂层与基体的剥离,腐蚀产物在涂层内的累积,也会导致涂层内孔隙和缺陷增多,促进涂层劣化。     

BEHAVIOUR OF α-NITROSO-β-NAPHTHOL IN HEMATITE FLOTATION

研究了α-亚硝基β-萘酚对赤铁矿的捕收性能及吸附规律,导出了吸附方程和吸附速率方程用药剂基团电负性理论计算以及红外吸收光谱法论述了其作用机理α-亚硝基β—萘酚主要是以N O键合原子与赤铁矿表面的Fe(Ⅲ)形成N O五元环螯合物而化学吸附.同时也兼有多层的,不均匀的物理吸附     

α—亚硝基β—萘酚浮选赤铁矿作用机理

研究了α-亚硝基β-萘酚对赤铁矿的捕收性能及吸附规律,导出了吸附方程和吸附速率方程用药剂基团电负性理论计算以及红外吸收光谱法论述了其作用机理α-亚硝基β—萘酚主要是以N O键合原子与赤铁矿表面的Fe(Ⅲ)形成N O五元环螯合物而化学吸附.同时也兼有多层的,不均匀的物理吸附     

SO_2和H_2O在Cu(100)表面共吸附行为的密度泛函计算(英文)

利用基于密度泛函GGA-r PBE方法的平板模型研究SO2和H2O在面心立方金属Cu(100)表面的共吸附行为。SO2和H2O在Cu(100)表面单分子吸附的计算结果表明,在覆盖度为0.25分子层和0.5分子层的情况,二者均不能以化学键的形式吸附在Cu(100)表面上。针对SO2和H2O在Cu(100)表面的共吸附行为,计算弛豫后的吸附结构、吸附能和电子性质(包括差分电荷密度、价电荷密度、Bader电荷分析和分态密度分析)。结果表明,覆盖度为0.25分子层时,H2O和SO2以化学吸附的形式各自吸附在表面不同Cu原子上;覆盖度为0.5分子层时,H2O分子解离成OH和H,OH吸附在表面Cu原子上,而H与SO2键合后共同远离表面。     

H2O分子在α-U(001)表面的吸附和解离

采用广义梯度密度泛函理论研究了H2O分子在α-U(001)表面上的吸附、扩散和解离。结果表明,H2O分子在α-U(001)表面的最稳定构型为平行于表面的顶位吸附结构,吸附能为0.58 eV。吸附作用主要源于H2O分子1b1轨道与表面U原子6d轨道的空间交叠,同时伴有弱的H2O 3a1-U 6d轨道交叠。近邻顶位间H2O分子的扩散能垒为0.20～0.23 eV,预示H2O分子易于在α-U(001)表面发生扩散迁移。OH+H解离吸附较分子吸附在能量上高1.24～1.39 eV,解离能垒为0.56～0.62 eV,预示一定热激活条件下,吸附H2O分子趋向解离形成OH基团和H原子。     

电弧离子镀Ni—Co—Cr—A1—Y—Si—B涂层的热腐蚀性能

采用电弧离子镀技术在DZl25和DSM11两种镍基高温合金基材上沉积Ni—Co—Cr—Al—Y—Si—B涂层，研究了高温合金基材及其Ni—Co—Cr—Al—Y— Si—B涂层在900℃的75％Na2SO4 25％K2SO4熔盐中的热腐蚀行为．结果表明，Ni—Co—Cr—Al—Y—Si—B涂层在热腐蚀过程中生成了连续致密的α—Al2O3氧化膜，有效地保护了合金基材免受腐蚀破坏，合金基材的热腐蚀性能对体系后期的热腐蚀行为影响很大．     

电流密度对Al/导电涂层/α-PbO2-CeO2-TiO2/β-PbO2-MnO2-WC-ZrO2复合电极材料制备和性能的影响

通过电化学氧化共沉积技术在A1/导电涂层/α-Pb O2-Ce O2-Ti O2基体上,制备了A1/导电涂层/α-PbO 2-Ce O2-Ti O2/β-Pb O2-MnO 2-WC-Zr O2复合阳极材料。通过能量色散X射线光谱（EDXS）、阳极极化曲线、暂稳态极化曲线（Tafel）、交流阻抗谱（EIS）、扫描电子显微镜（SEM）以及X射线衍射（XRD）等方法研究电流密度对复合阳极材料的化学组分、电化学活性和稳定性的影响。研究结果表明：在电流密度为1 A/dm2条件下制备的A1/导电涂层/α-PbO 2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2复合材料具有最低的析氧过电位（0.610 V,条件：500 A/m2）,最好的电化学活性,最长的使用寿命（360 h,条件：150 g/L H2SO4,2 A/cm2,40°C）以及最低的槽电压（2.75 V,条件：500 A/m2）。而且,随着电流密度的增加,涂层晶粒逐渐增大,MnO 2含量也逐渐降低,晶体结构几乎没有变化。     

氢对纳米不锈钢涂层钝化膜性能的影响

用动电位极化、恒电位极化、Mott-Schottky测量、X射线光电子能谱(XPS)分析及扫描电子显微镜(SEM)等手段研究了氢对纳米不锈钢涂层在0.5 mol/L NaCl 0.05 m01/L H2SO4溶液中腐蚀行为及钝化膜性能的影响.结果表明,氢与涂层表面吸附的OH-反应使OH-吸附减少,从而延迟了钝化膜的形成;氢使钝化膜的成分发生改变,钝化膜中的OH-/O2-的比率升高,因而钝化膜的点蚀敏感性增加;同时,氢促使钝化膜的介电常数增大,空间电荷电容增大,载流子密度增加,从而降低了钝化膜的稳定性.随着充氢量的增加,钝化膜的维钝电流和载流子密度随之增加,说明钝化膜的稳定性和涂层耐蚀性能都随之降低.     

电泳沉积壳聚糖/绿原酸复合涂层的耐蚀性能

目的 纯镁超声微弧氧化(UMAO)表面电泳沉积中药提取物绿原酸,提高纯镁的耐蚀性及生物活性.方法 采用电泳沉积(EPD)技术在UMAO表面上制备壳聚糖/绿原酸(CS/CA)涂层.采用扫描电子显微镜、X射线衍射仪、原子力显微镜、X射线光电子能谱、傅里叶变换红外光谱和接触角测量仪,研究不同样品的表面形态、组织结构,并研究涂层腐蚀行为,评价不同样品的耐蚀性.结果 UMAO/CS/CA涂层由Mg、MgO和Mg2SiO4相组成,含有O、C、Mg、Si和N元素,绿原酸涂层中有O—H、芳香烃键、C==O键和苯环的伸缩振动峰.中药提取物和壳聚糖之间的结合主要通过化学结合和物理吸附.UMAO/CS/CA涂层的接触角为104.1°,为疏水性表面.模拟体液环境下电化学腐蚀实验表明,Mg的腐蚀电流密度为1.7569×10?5 A/cm2,UMAO/CS/CA涂层的腐蚀电流密度为3.767×10?6 A/cm2,涂层的自腐蚀电流密度比Mg至少低1个数量级.UMAO/CS/CA涂层能更好地诱导钙磷物质沉积.结论 UMAO/CS/CA涂层既能减小腐蚀溶液与涂层表面的接触面积,又能起到隔绝溶液中离子的作用,使得涂层表面不容易被模拟体液润湿,涂层能为镁基体提供更有效的保护并具有优异的生物活性.     

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。