基于氧化钛纳米管模板电沉积氧化锌纳米棒

研究了氧化锌纳米棒在用二次阳极氧化法制备的二氧化钛纳米管模板表面的电沉积生长。与一次阳极氧化法对比,以二次阳极氧化法获得的氧化钛纳米管薄膜为模板,更有利于形貌均一、取向一致的ZnO纳米棒的电沉积生长,并且在电解质溶液中添加六次甲基四胺(HMT)、适当延长沉积时间均可提高ZnO纳米棒的结晶度和择优生长趋势。当沉积电压为1.0~1.5 V时,可获得形貌规则的ZnO纳米棒;而电压继续增大时,ZnO沿c轴择优生长趋势消失,电沉积产物氧化锌纳米棒由六边形氧化锌纳米片取代。     

采用溶胶-凝胶法在多孔氧化铝模板上制备立方相WO3纳米线

采用溶胶-凝胶法在纳米孔氧化铝模板上成功制备形貌各异的WO3纳米线.X射线衍射分析表明所制备的WO3纳米线为立方相结构.经扫描电子显微镜观察发现产物多数为菊花状WO3纳米线,其直径约10～80 nm,长约几微米.与空气气氛相比,氩气气氛更有助于WCl6三嵌段共聚物溶胶在多孔氧化铝模板上形成形貌各异的WO3纳米线.     

热处理气氛对生成纳米碳化钽的影响及机理

在真空、氢气和氩气气氛中,使用液相先躯体法制备得到纳米碳化钽(TaC)粉末,并使用XRD、TEM、比表面积分析仪分析了在不同热处理气氛中得到的产物的物相、显微形貌及比表面积.通过对产物的对比和分析,说明热处理气氛对生成纳米TaC的影响,并对其机理进行探讨.在真空中,气体产物CO被排到炉外,从而加速生成TaC的反应,使之在1300℃时生成比表面积为28m2/g、平均粒径约50nm、略有团聚的TaC.在氢气中,CH4作为碳气相迁移的载体加速反应进行,使之在1300℃时生成比表面积为12m2/g,平均粒径约100nm、略有团聚的TaC.在氩气中,没有促进反应进行的因素,在1400℃时才可生成比表面积为61m2/g,平均粒径约50nm、分散较好的TaC.     

阳极氧化铝样模法制备纳米线阵列的发展趋势

在具有纳米孔洞的阳极氧化铝(AAO)模板上，电沉积金属和半导体微粒，可制备出高度有序的一维金属半导体纳米线阵列。样模法制备纳米材料是国内外竞相研究的热点，阳极氧化铝膜以其良好的高密度纳米孔径正逐渐引起人们的关注。     

有序多孔氧化铝模板及 ZnO 沉积膜的制备与表征

采用二次阳极氧化法制备有序多孔氧化铝模板(AAO),探讨了氧化时间、磷酸溶液浸泡后处理对氧化铝表面形貌的影响。以AAO为模板沉积ZnO薄膜,通过SEM,XRD,EDS,AFM等技术对氧化铝模板及ZnO薄膜进行表征,结果表明,有序多孔层为非晶态氧化铝。研究了以AAO为模板沉积ZnO薄膜作光阳极的染料敏化太阳电池的光电转换性能,得出其转换效率为0.34%。     

含钙阳极氧化铝的制备及其体外性能

通过阳极氧化与电化学沉积复合制备方法获得了含钙阳极氧化铝膜.采用扫描电镜和电子能谱仪分别研究了不同条件制备的含钙阳极氧化铝膜的形貌与元素组成;采用等离子体原子发射光谱仪、pH计和X射线衍射仪研究了含钙阳极氧化铝膜在模拟体液中的化学稳定性与诱导行为.结果表明:当钙盐浓度为10 g/L时,采用不同电化学沉积电压,含钙阳极氧化铝膜的钙含量约在1%～10%间变化;含钙阳极氧化铝膜在模拟体液中稳定性很好,并能诱导骨状磷灰石的生成.     

化学溶液沉积法制备氧化锌纳米棒阵列

利用化学溶液沉积法,以Zn(CH3COO)2·2H2O、六次甲基四胺为原料制备了规整而有序的ZnO纳米棒阵列.用FESEM、XRD等考察种子液浓度、反应溶液浓度等对2nO纳米棒表面形貌、晶粒大小及晶体结构的影响.结果表明,制备的ZnO纳米棒的直径随反应溶液浓度增大而增大,纳米棒垂直于基底沿着(002)面生长.紫外可见吸收光谱表明,ZnO纳米棒对300～400nm波长范围的光有很强吸收性;在500～700nm有一个相对比较弱的吸收峰,光致发光谱图中在384 nm处有一个近紫外带边发射峰.     

制备纳米材料的多孔型氧化铝膜板的阳极氧化工艺研究

多孔型阳极氧化铝膜是制备纳米材料的理想模板。以草酸为电解液研究了高纯铝的阳极氧化工艺,采用扫描电镜对多孔型阳极氧化铝膜的表面及断面形貌进行表征。讨论了阳极氧化电压和电解液温度对多孔阳极氧化铝膜的孔径及孔密度的影响。对氧化膜厚度的测定结果表明,当氧化时间为7 h时,氧化膜厚度达到最大值36μm。     

阳极氧化铝模板制备过程探究

为了实现对多孔阳极氧化铝模板的孔径和孔间距的有效调控,并找出对孔径大小及表面孔规整度的影响因素,获得简易可行、成功率高且高度有序模板的制备工艺,对现有的两步阳极氧化法及电化学抛光工艺进行了探究,通过改进前处理工艺,对电解液温度,氧化时间等参数进行调整,并对铝片样品表面形貌变化过程进行了表征。结果表明:碱洗处理和电化学抛光等氧化前预处理工艺,可以明显提高阳极氧化铝模板孔的规整度并增大了出孔面积,提高制备的成功率。     

碳纳米管模板法制备碳化钨纳米棒的可行性研究

采用碳纳米纤维管,WO3和I2为原料对碳纳米管模板法制备碳化钨纳米棒的可行性进行了研究,并对其制备原理进行了分析,提出了因碳纳米管产生的隧道效应,挥发性钨源被不断吸入纳米管内并与管壁发生碳化反应生成碳化钨棒的反应模型;在实验结果的基础上,进一步提出了纳米棒强化的新概念硬质合金的制备新方案。     

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。