La3+、Ce4+掺杂对纳米TiO2-Fe2O3凝胶相变过程的影响

采用sol-gel法制备了掺杂La3+、Ce4+的TiO2-10wt%Fe2O3复合粉体,利用TG-DTA和XRD分析对凝胶的相变过程进行了表征。结果表明:TiO2-10wt%Fe2O3凝胶在450℃发生非晶态向锐钛矿相的转变,而在500℃煅烧2 h后未发现锐钛矿相向金红石相转变;随La3+、Ce4+掺杂量的增加,锐钛矿晶粒呈现细化→长大的趋势;随La3+掺杂量的增加,对Fe2O3微晶的生成作用呈现促进→抑制的趋势,而对Fe3O4微晶的生成呈现抑制→促进的趋势;随Ce4+掺杂量的增加,对Fe2O3微晶的生成作用随掺杂量的增加呈促进→抑制→促进的趋势,而对Fe3O4微晶的生成呈现抑制→促进的趋势;La3+、Ce4+掺杂对TiO2相变过程有重要影响。     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Lu2O3/TiO2/Nb2O5共稳定ZrO2热障涂层材料研究

采用Lu2O3/TiO2/Nb2O5作为ZrO2热障涂层材料的稳定剂,研究Lu2O3/TiO2/Nb2O5共稳定ZrO2(15%LTNSZ)热障涂层材料在900℃、40 mol%V2O5+60 mol%Na2SO4熔盐中的热腐蚀行为。结果表明:8%YSZ热障涂层材料热腐蚀2 h后,t相ZrO2全部相变为m相ZrO2,热腐蚀产物为尺寸较大的YVO4晶体;15%LTNSZ热障涂层材料热腐蚀20 h后,m相ZrO2的比例仅为5.5%,热腐蚀产物为尺寸较小的LuVO4晶体。与Y2O3稳定剂相比,Lu2O3/TiO2/Nb2O5稳定剂使ZrO2在40 mol%V2O5+60 mol%Na2SO4熔盐中的抗热腐蚀性能提高1个量级以上。     

Fe2O3含量对CaO-Al2O3-SiO2系微晶玻璃显微组织与力学性能的影响（英文）

采用差热分析(DTA)、X射线衍射(XRD)、扫描电镜(SEM)、电子顺磁共振(ESR)和Mssbauer谱等技术研究Fe2O3含量对CaO-Al2O3-SiO2系微晶玻璃显微组织与力学性能的影响。结果表明:Fe2O3的加入不改变CaO-Al2O3-SiO2系微晶玻璃析出的主晶相类型,但使体系的析晶峰温度降低,析晶活化能增加和析出晶体的粒度减小。ESR测试结果表明,Fe2O3的加入会因轴向扭曲造成分相,从而促进析晶;同时,Fe2O3的加入能更好地调整CaO-Al2O3-SiO2系微晶玻璃网络内部结构,使Fe3+进入比四面体对称性更高的八面体配位,有利于抗弯强度的增大。Mssbauer测试结果表明,Fe3+和Fe2+在CaO-Al2O3-SiO2系微晶玻璃存在不同的配位,且微晶玻璃的抗弯强度随Fe3+六配位数的增多而增大;同时,Fe2+和Fe3+相互作用的增强也有利于微晶玻璃抗弯强度的增大。在核化温度为700°C、核化时间为2 h、晶化温度为910°C和晶化时间为3 h的热处理条件下,样品的显微硬度达到HV 896.9,抗弯强度达到217 MPa。     

分步碳包覆合成高密度LiFePO4/C复合材料

采用分步碳包覆法合成LiFePO4/C复合材料。首先,将原料Fe2O3、NH4H2PO4和葡萄糖经过固相反应合成Fe2P2O7/C复合材料,再将Fe2P2O7/C与前驱体Li2CO3、葡萄糖混合,通过二次碳包覆工艺合成LiFePO4/C复合材料,并考察合成温度对LiFePO4/C复合材料电化学性能的影响。采用X射线衍射、扫描电镜、差热-热重分析、电化学阻抗谱(EIS)和充放电测试对材料的性能进行表征。结果表明:以制取的Fe2P2O7/C为前驱体合成的LiFePO4/C复合材料具有较好的物理和电化学性能,材料的振实密度达1.26 g/m3,0.1C放电容量为158.3 mA.h/g,1C初次放电比容量达到140 mA.h/g。     

熔盐电解法制备单一Sm2Fe17合金相的机理研究

选择在LiF-CaF₂-SmF₃熔盐体系中,采用熔盐电解法在1160℃下通过恒电流在Fe阴极表面获得了不同厚度(17.22～40.34μm)的Sm₂Fe₁₇合金层,同时通过循环伏安法与方波伏安法研究了Sm³⁺在W与Fe阴极上的电化学行为。结果表明,Sm³⁺无法单独沉积于W电极上,Sm³⁺在铁阴极上的还原为Sm⁰分为2步,首先在-0.33V(vs.Cr/Cr₂O₃)发生Sm³⁺还原为Sm²⁺的可溶-可溶型反应,然后当电极电势超过-0.78V(vs.Cr/Cr₂O₃)时Sm²⁺开始在阴极界面处上发生欠电势还原,在Fe电极表面生成Sm₂Fe₁₇合金,这是由于在Sm₂Fe₁₇合金中降...     

合成温度对正极材料Li3V2（PO4）3/C性能的影响

以V2O5、NH4H2PO4、Li2CO3和C6H8O7·H2O为原料,采用溶胶-凝胶法在600～800℃下合成了锂离子电池正极材料Li3V2(PO4)3/C,利用XRD和蓝电测试系统对材料进行表征,研究了合成温度对材料电化学性能的影响。结果表明:650℃下合成产物中开始出现Li3V2(PO4)3相,700、750和800℃下合成纯相的Li3V2(PO4)3正极材料;750℃合成的样品在放电电流密度为0.1C下首次放电容量为123.5mAh·g-1,并且随电流密度增大到10C时也有较好的循环稳定性。     

激光熔覆制备NiCr/Cr3C2-WS2-CaF2复合材料涂层

以NiCr/Cr3C2-WS2-CaF2复合合金粉末为原料,采用激光熔覆技术,在1Cr18Ni9Ti不锈钢表面制备了高温自润滑耐磨复合材料涂层。采用XRD、SEM和EDS等手段对所制备复合涂层的显微组织进行了分析,并分别测试了涂层在室温、300℃、600℃时的干滑动磨损性能。结果表明:该复合涂层由γ-(Ni,Fe)固溶体基体、Cr7 C3/WC增强相及CrS/WS2润滑颗粒组成;室温时,涂层的磨损率较大;随着温度的升高,由于润滑转移膜的形成,涂层拥有良好的减摩耐磨性能。     

电泳-预氧化扩散处理法制备NiO/NiFe2O4涂层及其形成机制

先采用电沉积?电泳方法在Ni基体高温合金上制备电镀Ni/电泳Fe2O3复合涂层,再通过后续空气中进行的高温预氧化处理方法来获得NiO/NiFe2O4复合氧化物涂层。利用DSC、SEM、EDS和XRD等检测手段分析预氧化温度对涂层的结构、微观形貌、元素分布及相组成等影响,并对涂层形成的反应机理及预氧化动力学进行讨论。结果表明:经1 000、1 100和1 200℃下氧化4 h后,氧化膜中均生成NiO和NiFe2O4。氧化温度为1 000℃时涂层表面还存在没有参与反应的Fe2O3,但随氧化温度的升高,Fe2O3层随之消失。温度为1 100和1 200℃时氧化膜中的NiO、NiFe2O4相与镀Ni基体之间形成了冶金结合,并且通过扩散在NiO相内部形成了NiFe2O4析出相。Ni基体以及电镀Ni/电泳Fe2O3复合涂层在1 000℃预氧化时单位面积上的质量增加随时间增加,大体遵循抛物线规律,且电镀Ni/电泳Fe2O3复合涂层单位面积上的质量增加大于镀Ni基体的。涂层的厚度与氧化质量增加随预氧化扩散温度的提高而增加。     

锰掺杂对锂离子电池正极材料Li3V2（PO4）3/C性能的影响（英文）

采用溶胶-凝胶法合成Li3V2-2/3xMnx(PO4)3(0≤x≤0.12)。采用XRD、SEM、XPS、恒流充放电和电化学阻抗谱(EIS)研究Mn掺杂对Li3V2(PO4)3/C结构和电化学性能的影响。XRD研究表明:掺杂少量的Mn2+不会影响材料的结构,所有样品均具有单一相态的单斜结构(P21/n空间群)。XPS分析表明:在Li3V1.94Mn0.09(PO4)3/C中,V和Mn的化合价分别为+3和+2,原料中的柠檬酸在煅烧过程中分解成C而残留在Li3V1.94Mn0.09(PO4)3/C中。电化学测试表明:掺杂Mn改善了电极材料的循环性能和倍率性能,正极材料Li3V1.94Mn0.09(PO4)3/C表现出最好的循环稳定性和倍率性能。在40mA/g的放电电流密度下,循环100次后,Li3V1.94Mn0.09(PO4)3/C的放电容量从158.8mA·h/g衰减到120.5mA·h/g,容量保持率为75.9%,而未掺杂样品的放电容量从164.2mA·h/g衰减到72.6mA·h/g,容量保持率为44.2%。当放电电流密度增加到1C时,Li3V1.94Mn0.09(PO4)3/C的初始放电容量仍能达到146.4mA·h/g,循环100次后,放电容量保持为107.5mA·h/g。EIS测试表明,掺杂适量的Mn2+减小了电荷转移阻抗,这有利于Li+的脱嵌。     

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.