还原温度对用MR-EMR法制备Ta粉的影响

电解电容器用钽粉的工业生产方法是用金属Na还原K2TaF7的金属热还原法（MR法）。该法属炉批式生产，耗时耗电，生产率低，且K2TaF，和Na在反应容器内直接接触，反应位置难以控制，Ta在容器壁上附着，使Ta的回收率低。因此，为了提高高纯Ta粉的产量，需进行析出物的形态、反应位置的控制以及连续生产方式等课题的研究。     

低品位钽铌原料的湿法冶金新工艺研究

研究了低品位钽铌原料的湿法处理新工艺。在新工艺中用新型分解试剂替代HF和H2SO4在300℃条件下分解低品位钽铌原料,其分解液采用甲基异丁基酮（MIBK）在低浓度酸条件下萃取钽、在高浓度酸条件下萃取铌,然后对钽液、铌液进行过氧化及沉淀后焙烧,得细粒径高纯度Ta2O5,Nb2O5产品,或者对钽液进行结晶,可制得高纯度的K2TaF7产品。     

钨精矿中杂质元素ICP-MS测定方法的研究

采用电感耦合等离子质谱技术，研究了钨精矿中Sn，P，Ca，Nb，Ta，Mo，Cu，Pb，Zn，As，Mn，Bi，Fe，Sb 14种杂质元素含量的质谱分析方法。钨精矿样经NaOH-Na2O2碱熔后，加入硝酸，钨以钨酸的形式从溶液中沉淀而分离，消除了钨基体的干扰。在试样溶液中加入内标元素Sc，In，Tl，采用内标法进行校正，有效克服了基体效应、接口效应及仪器波动所产生的影响：通过优化仪器工作参数，选择适当的待测元素的同位素，有效地克服了因质谱干扰所带来的影响。方法的加标回收率为90．5％～101．5％，相对标准偏差为1．2％～7．8％，分析结果与按国家标准方法分析的结果相吻合，且具有快速、简便、准确等特点，可用于钨精矿及钨产品中杂质元素含量分析。     

W—Ta合金单晶在生长方位的各种结晶学取向时的亚组织与浓度的关系

从W-Ta系二元合金单晶亚组织生长和形成理论的观点来看，体心立方晶格相内的熔化度图和结晶行为是很重要的，可以借助于它们来制取单晶，并且研究在全部浓度范围内单晶组织和性能与浓度的关系，其中包括从纯钨到纯钽，W-Ta合金单晶是最耐热的金属材料之一；即使在高于1800℃的温度下，它也是高度稳定的。业已得出，钨基和钽基两个系统的物理-化学参数如下： 金属 基体 添加物, 杂质 k m, K/at% m(1-k)/k, K/at% △r/r W W W Ta Ta Ta Re C W C 0.81 0.59 0.03 1.25 0.565 -6 -13 -31 7 -12.5 1.41 9.0 10 1.4 9.6 4.2 -2.1 -4.2 …     

钽或铌酸盐化合物生产工艺研究

提供了一种经过改进的生产钽酸盐或铌酸盐化合物的新工艺。该工艺是用高纯H2TaF7或H2NbF7和H2NbOF5溶液经沉淀等一系列反应后，先生产一种含钽或铌的化合物，然后再将该化合物与高纯碳酸盐或氢氧化物进行均相混料，经低温烘干、烧结、酸洗、水洗、过滤、烘干后，得到钽或铌酸盐化合物。用新工艺生产的钽或铌酸盐化合物用于制备钽或铌酸盐晶体时，从根本上克服了传统方法固体粉末混料不均匀等缺点所造成的质量不稳定的问题。     

采用氧化物生产钽粉和铌粉的新工艺

40多年来,世界各地供应的电容器级钽粉一直采用钠还原7价氟化钽钾(K2TaF7)的方法制造,该工艺过程通常是在高于800℃和搅拌的熔融盐介质中进行。钽生产厂商采用这种工艺学会了如何生产表面积愈来愈大的钽粉,来满足电子工业对较高容量效率电容器的需求。但是,目前钠还原工艺技术已达到了成熟阶段,采用这种工艺技术很难继续提高粉末的性能。最近,德国的赫尔曼? 斯达克(H. C. Starck)集团公司开展了一项寻找生产下一代钽粉有潜力的其它方法,以继续满足电子工业对钽粉较高表面积的要求。他们对生产用于电容器的其它金属粉末(如铌及其合…     

钽铌电子材料新进展（I）

代表中国钽铌工业整体水平的宁夏东方有色金属集团有限公司，近年来，研究了钽粉的微观结构，开发出降低杂质含量，改善物理性能等新技术以及Ta2O5钠还原制取高比容钽粉、TaCl5低温钠还原制取纳米级钽粉的新工艺方法；研制并生产出性能优良的、适用于钽电容器的高比容钽粉，同时也开发了高比容铌粉、一氧化铌粉的制造新技术，制得高性能的电容器级铌粉和一氧化铌粉，为铌电容器作为一种新型电容器产业参与竞争提供了优质的基础材料。     

晶粒尺寸对粉冶钽及熔铸钽和钽-钨合金流变应力的影响

人们对担基材料的变形性能模拟试验很感兴趣．迄今为止，一般的研究重点主要为铝和袒一钨板材．在袒中添加钨，作为固溶强化剂．可明显地改变产品的再结晶组织．但在钽和钽合金板材中，这一特征常常被忽略．除由铸锭生产的轧材外，人们对由袒粉生产的产品的功能试验也很感兴趣．虽然粉冶钽与熔铸袒相比，其间隙元素含量较高，但粉冶担易成形，并且粉冶钽锻件晶粒细小，流变应力高，塑性好．虽然已经进行了大量的研究工作，建立了合金成分、组织、温度、应变速度及冲击预应变对望的力学性能的影响，但晶粒尺寸对包和袒合金强度影响的报道却很…     

钽资源及其生产综述（英文）

钽(Ta)是一种关键高科技金属，在电工电子、航空航天等战略新兴产业中都有重要应用。当前尚无钽的替代材料，近20年来全球钽供应危机不断加剧。本工作对钽资源及其生产进行全面综述。地壳中已查明Ta储量不足300 kt，钽的提取以钽精矿为主要原料，此外，锡冶炼渣、锂矿石、废钽产品也能生产约37%的金属钽。钽的生产是一个高耗能过程，HF浸出-溶剂萃取-K₂TaF₇还原工艺是工业上制Ta最常用的工艺，但较高的生产成本和大量废弃物的产生是制约该方法可持续发展的重要因素。钽的清洁生产及高效回收将受到持续关注。     

高纯纳米氧化钽的制备

以自制高纯乙醇钽为原料，通过水解、干燥与煅烧生产粒度约35nm的高纯Ta2O5纳米粉。研究了水解过程中乙醇钽浓度、温度、加料时间对产品粒度的影响以及煅烧温度与时间对Ta2O5晶形的影响。选取水解最佳条件为：乙醇钽浓度1.0mol／L，水解温度50℃左右，加料时间约15min。加完后，搅拌5min，接着加入氨水溶液调节pH值到8～9，同时升温至80℃-85℃保温30min；煅烧温度800℃，时间2h。得到的Ta2O5产品粒度约35nm，纯度〉99．997％。     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.