Effect of SiO2 addition on the dielectric properties and microstructure of BaTiO3-based ceramics in reducing sintering

The effect of SiO2 doping on the sintering behavior,microstructure,and dielectric properties of BaTiO3-based ceramics has been investigated.Silica was added to the BaTiO3-based powder prepared by the solid state method with 0.075mo1%,0.15mo1%,and 0.3mo1%,respectively.The SiO2-doped BaTiO3-based ceramic with high density and uniform grain size were obtained,which were sintered in reducing atmosphere.A scanning electron microscope,X-ray diffraction,and LCR meter were used to determine the microstructure as well as the dielectric properties.SiO2 can form a liquid phase belonging to the ternary system of BaO-TiO2-SiO2,leading to the formation of BaTiO3 ceramics with high density at a lower sintering temperature.The SiO2-doped BaTiO3-based ce-ramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h.The dielectric constants of the sample with 0.15mo1% SiO2 addition sintered at 1220℃ is about 9000.Doping with a small amount of silica can improve the sinter-ing and dielectric properties of BaTiO3-based ceramics.     

Preparation and electrochemical characterization of activated carbons by chemical-physical activation

A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m²/g and 0.308 4 cm³/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance. Foundation item: Project(2007BAE12B01) supported by the National Key Technology Research and Development Program of China     

浅析配电设备运行中的安全维护

配电设备是电力系统的重要组成部分,配电设备的正常运行是保证配网能够安全可靠供电的关键所在.通过对配电设备的巡视检查,可以了解其运行状况,及时发现缺陷或出现的异常情况,从而采取有效措施来防止事故的发生和扩大,以保证设备能够安全可靠的正常供电.运行人员通常较为关注油浸变压嚣及柱上开关等设备的运行维护,本文就日常工作中容易忽视的配电设备运行维护要点进行分析.     

陶瓷电容器的制备工艺概述

简介了新型陶瓷电容器的优点、功能、类型和发展现状及表面层陶瓷电容器、表面层型陶瓷电容器和晶界型陶瓷电容器的产生机理和区别，和影响陶瓷电容器性能的诸多因素，如显微结构、掺杂元素和包覆改性等；回顾了国内外陶瓷电容器的烧成工艺发展历史，如高温一次烧成、低温一次烧成、独石法和激光辐射法等；展望了陶瓷电容器在21世纪的研究和应用前景。     

车用启动超级电容器

本实用新型为一种车用启动超级电容器，超级电容器芯子由包裹隔膜的烧结式氧化镍正极片，连续化活性碳纤维布负极和集流支撑的薄镍片构成。电容芯子通过制作、焊接电流端子后，置于塑料壳体内，注入电解液，封口便得超级电容器成品。该超级电容器具有较高的功率密度和能量密度，且质量轻，成本低，寿命长，适合做并种类型车辆的启动能源，推广应用具有很好价值。     

磺化石墨烯/多壁碳纳米管/二氧化锰复合材料的制备及其在超级电容器中的应用

通过冷冻干燥法制备了磺化石墨烯/多壁碳纳米管(简称碳纳米管)三维自支撑材料,并通过水热法成功在三维材料表面负载二氧化锰纳米颗粒。采用了具有良好导电性和水溶性的磺化石墨烯和碳纳米管作为二氧化锰的支撑基体,且所制备的材料呈现三维多孔结构,克服了传统二氧化锰材料导电性差等缺点。扫描电镜结果表明,石墨烯纳米片和碳纳米管相互支撑形成三维多孔结构;透射电镜结果表明,二氧化锰成功负载在石墨烯/碳纳米管材料之上;循环伏安测试表明,复合材料呈现良好的双电层电容特征;充放电测试结果表明,复合材料的具有优良的比电容。     

静电纺丝法制备高性能Ni_3V_2O_8纳米纤维超级电容器

利用快速有效的静电纺丝法,制备聚乙烯吡咯烷酮(PVP)/乙酸镍-乙酰丙酮氧钒(C10H14O5V)复合纳米纤维,经高温焙烧后得到Ni3V2O8纳米纤维。借助XRD、EDS、TGA、FESEM和TEM表征技术对纳米纤维的结构和形貌进行表征。XRD、EDS和TGA测试证明实验制备得到Ni3V2O8。FESEM和TEM结果表明Ni3V2O8呈一维纳米纤维结构,其直径在200~300nm之间,并由粒径为20~25nm的纳米粒子组成。电化学测试结果表明Ni3V2O8纳米纤维具有优异的性能,在1A/g时比电容达到1 152F/g,在5mV/s时达到1 345F/g,经过2 000次充放电测试(2A/g)后保持率为84.08%。其一维多粒子的独特结构能提高稳定性,缩短离子扩散距离以及利于电子传递。综合表明,Ni3V2O8纳米纤维是理想的高性能赝电容器电极材料。     

石墨烯/裂解炭复合凝胶的制备及其在电化学电容器中的应用

在常温常压条件下制备了氧化石墨烯/多巴胺复合三维凝胶结构,并通过高温煅烧得到了石墨烯/裂解炭复合结构。采用扫描电镜和比表面积测试发现裂解炭的包覆有效降低了石墨烯片层的团聚,得到的材料表现出了较大比表面积;通过恒流充放电测试发现所制备的材料具有较好的电容性能。     

中科院高性能石墨烯基超级电容器研究获进展

作为新型储能器件,超级电容器具有功率密度高、充电时间短、使用寿命长等优点。然而,其能量密度一直受限于电极材料的性能。     

变电站电容器组的故障分析及维护

1 变电站10 kV电容器组现状 电容器组在运行或投切过程中发生故障主要集中在电容器上,有电容器漏油、绝缘不良、外壳鼓肚、熔断器熔断、表面放电闪络、爆炸等[1-3].随着地区负荷的不断增长,变电站的数量不断增加,电容器组构建、安装、维护及试验检测水平也在不断提高,典型故障发生率大大降低.去年,对本地区所辖一百多座110 kV及以上变电站进行了共计24次电容器组消缺、诊断试验,比前一年度减少4次,但有2起非典型故障引起的电容器组开关跳闸抢修工作. 因此,对电容器组故障进行有效分析总结并采取针对性维护措施,保障变电站安全运行是非常必要的.