Leaching of vanadium,sodium, and silicon from molten V-Ti-bearing slag obtained from low-grade vanadium-bearing titanomagnetite

The water leaching process of vanadium, sodium, and silicon from molten vanadium-titanium-bearing (V-Ti-bearing) slag obtained from low-grade vanadium-bearing titanomagnetite was investigated systematically. The results show that calcium titanate, sodium aluminosilicate, sodium oxide, silicon dioxide and sodium vanadate are the major components of the molten V-Ti-bearing slag. The experimental results indicate that the liquid-solid (L/S) mass ratio significantly affects the leaching process because of the respective solubilities and diffusion rates of the components. A total of 83.8% of vanadium, 72.8% of sodium, and 16.1% of silicon can be leached out via a triple counter-current leaching process under the optimal conditions of a particle size below 0.074 mm, a temperature of 90°C, a leaching time of 20 min, an L/S mass ratio of 4:1, and a stirring speed of 300 r/min. The kinetics of vanadium leaching is well described by an internal diffusion-controlled model and the apparent activation energy is 11.1 kJ/mol. The leaching mechanism of vanadium was also analyzed.     

Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

Low-cost iron-based shape memory alloys (SMAs) show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure torsion (HSHPT) process on the microstructural evolution of an Fe–Mn–Si–Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations characteristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence of ε-martensite with an HCP crystal structure and γ-phase with an FCC structure.     

球形微米级CaCO3的制备

球形微米级ＣａＣＯ３的制备赵振国丁丁（北京大学物理化学研究所,北京,１００８７１）关键词ＣａＣＯ３粉体;粉体制备中图分类号Ｏ６４８．１５几何尺寸为微米级的微粉体开始出现表面效应,有的有实用价值。ＣａＣＯ３微粉可作为纸张和塑料制品的添加剂。以高分子量低...     

用流延法制备LSGM电解质膜的研究

稀土钙钛矿型氧化物LaGaO3是固体氧化物燃料电池(SOFC)研制中具有应用前景的固体电解质材料,用固相反应法制备La0.85Sr0.15Ga0.85Mg0.15O2.85粉末,其水溶液pH值出现先升后降的规律,由于粉末在水溶液中很稳定,因而可采用水基浆料制备电解质膜。在La0.85Sr0.15Ga0.85Mg0.15O2.85粉末中加入适量分散剂、粘结剂、塑化剂、去泡剂和溶剂,用流延法制备LSGM厚膜,其厚膜完整、无宏观缺陷及可以卷曲,经过1500℃、10～24h烧结后可得到致密的LSGM厚膜。     

尿素均相沉淀法制备均分散氧化亚镍粉末(Ⅰ)——前驱体的制备研究

采用尿素均相沉淀法制得了均分散的氧化亚镍前驱体粒子．系统考察了镍离子浓度、尿素浓度、反应温度、反应时间、起始ｐＨ值及分散剂等因素对前驱体粒子形成的影响规律．结果表明,在一定条件下所得的前驱体粒子是一种化学组成为Ｎｉ２（ＣＯ３）（ＯＨ）２的晶态物质,粒子呈球形,且粒度分布均匀．     

以SiHCl3为工作介质生产高丰度28Si

为了获得高丰度的28S i同位素,生产高纯度的单晶硅,利用气体离心机对硅同位素进行离心分离。通过对S iH-C l3中组成元素的不同同位素丰度的分析,计算了天然S iH-C l3中不同相对分子质量的分子组成。分析结果表明:虽然氯有两种同位素,但也可以将S iHC l3作为分离28S i同位素的工作介质。通过4台离心级联的分离实验,得到了28S i丰度达到99%的S iHC l3样品。离心分离得到的高丰度S iHC l3不用经过化学转化就可以直接用于单晶硅的生产。实验结果表明,采用离心法分离S iHC l3可以得到高丰度28S i。     

基于ATT7022A的Y/Δ切换抽油机节能控制器的研制

Y/Δ转化器在低负载率时,节电效果较好。可控硅调压控制器在高负载率时,节电效果较好。采用高精度三相电能计量芯片ATT7022A,设计了一种结合两者优点的抽油机节能控制仪。对抽油机电动调压节能系统的软硬件设计做了较详细的分析。通过在多口油井上安装Y/Δ可控硅调压组合式抽油机节能控制仪,并对5口井进行了现场对比测试,单口井年节电约2.1万kW.h。     

车用大功率电力电子器件研究进展

 车用电机驱动变流器是电动汽车电机驱动的关键部件,大功率电力电子器件是其核心。对比分析了国内外电动车辆用电机驱动变流器的拓扑结构、变流器控制特点及体积功率密度等关键指标,指出车用电机驱动变流器的技术创新重点在于硅基绝缘栅双极性晶体管(IGBT)芯片及封装技术持续改进碳化硅(SiC)器件的应用。综述了硅基IGBT芯片的演进和IGBT模块封装技术的创新,介绍了碳化硅器件的技术特点。     

Dielectric properties of spark plasma sintered AlN/SiC composite ceramics

In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a second conductive phase. All ceramic samples were prepared by spark plasma sintering (SPS) under a pressure of 30 MPa. AlN composite ceramics sintered with 30wt%–40wt% SiC at 1600℃ for 5 min exhibited the best dielectric loss tangent, which is greater than 0.3. In addition to AlN and β-SiC, the samples also contained 2H-SiC and Fe₅Si₃, as detected by X-ray difraction (XRD). The relative densities of the sintered ceramics were higher than 93%. Experimental results indicate that nano-SiC has a strong capability of absorbing electromagnetic waves. The dielectric constant and dielectric loss of AlN-SiC ceramics with the same content of SiC decreased as the frequency of electromagnetic waves increased from 1 kHz to 1 MHz.     

多孔硅在射频/微波电路中的研究进展

多孔硅介质膜在射频/微波电路中具有很好的应用前景. 阐述了多孔硅作介质膜的优点,比较研究了不同厚度的多孔硅厚膜上平面电感器的性能参数比较和不同介质膜上螺旋电感性能比较,介绍了多孔硅在射频/微波电路的研究进展,并对存在的主要问题作了讨论.