碳纳米管的分散方法与分散机理

要发挥碳纳米管的优异性能,如何均匀分散碳纳米管是首先要解决的关键性问题。通过研究碳纳米管的团聚体形态,看出碳纳米管团聚体为一维纳米线团聚态,比普通颗粒粉体的零维团聚态更复杂。碳纳米管分散方法大体上分为物理法与化学法两大类,对比研究碳纳米管的各种分散方法,分析碳纳米管的分散机理,提出了均匀分散碳纳米管要满足3个必要条件:打散碳纳米管团聚体、剪断长碳纳米管、保持碳纳米管分散状态。剪切挤出分散法可以较好地满足这3个条件,制备出均匀分散的碳纳米管复合粉体。     

磁电机定子插线自动化生产线开发

针对现有磁电机定子滴胶插线生产工艺中出现的生产效率低、成品率不高、工人劳动强度大等问题,选取了一种生产需求量最大的的定子产品的插线生产过程作为自动化改造对象。改造后的结果表明,使用新开发的自动化装置实现了全过程全自动控制,生产成品率不低于99%,生产效率提高330%。     

Enhanced visible light photocatalytic activity of QDS modified Bi2WO6 nanostructures

Bi₂WO₆ (BWO) nanostructures with QDS dispersed on single crystalline nanosheets were successfully prepared by a facile solvothermal method. The product possessed large surface area of 60 m²/g and exhibited excellent visible light absorption with a blue shift from 2.54 eV to 2.75 eV. The photocatalytic efficiency of the sample was six times that of nanoparticles assembled BWO nanostructures and three times that of nanoplates assembled BWO nanostructures. The photocatalytic mechanism for degradation of dyes over QDS modified BWO nanostructures was discussed, which revealed the important role of QDS in the generation, migration and consumption of the photogenerated electrons and holes.     

Copper-based electrodes for IT-SOFC

Copper and gadolinium doped ceria (GDC) anode supported fuel cells were co-sintered at relatively low temperature (900 °C) and successfully tested in the intermediate temperature (IT) range. The GDC electrolyte densification was promoted by a compressive strain induced by increasing the anodic thickness and was evaluated by SEM investigation. Instead of more commonly used La_0.8Sr_0.2Fe_0.6Co_0.4O_3-δ, strontium and copper-doped lanthanum ferrite La_0.8Sr_0.2Fe_0.8Cu_0.2O_3-δ (LSFCu) mixed with 30 wt% GDC (LSFCu-GDC) was employed as cathodic material. Preliminary tests on Cu-GDC/GDC/LSFCu-GDC single cells showed promising results at temperature as low as 650 °C using hydrogen as fuel.     

Improvement of cycle stability at elevated temperature and high rate for LiNi0.5−xCuxMn1.5O4 cathode material after Cu substitution

A series of Cu-substituted LiNi_0.5−xCu_xMn_1.5O₄ (x = 0, 0.03, 0.05 and 0.08) spinels have been synthesized using a sol–gel method. The results demonstrate that when x = 0.05, the sample (LiNi_0.45Cu_0.05Mn_1.5O₄) exhibits the best electrochemical performance, achieving 124.5 mAh g⁻¹ and 115.0 mAh g⁻¹ at the discharge rates of 5 C and 20 C with the capacity retention of 97.7% and 95.7% after 150 cycles, respectively. Besides, the excellent cycle stability at 55 °C has been demonstrated to retain 96.8% of the maximum attainable discharge capacity (127.3 mAh g⁻¹) at the discharge rate of 5 C after 100 cycles. These data indicate that the LiNi_0.45Cu_0.05Mn_1.5O₄ cathode material has the real potential to be used for high power and high energy lithium ion battery in electric vehicle applications.     

Formaldehyde-, Benzene-, and Xylene-Sensing Characterizations of Zn–W–O Nanocomposite Ceramics

Zn–W–O nanocomposite ceramics with the whole concentration range ( W at.%=0%, 1%, 5%, 25%, 50%, 75%, 95%, 99%, and 100%) have been fabricated by the sol–gel method, starting from zinc acetate dihydrate, ammonium tungstate, monoethanolamine (MEA), and anhydrous ethanol. Nanocomposites, that were sintered at 650°C in a conventional oven for 120 min were ultrasonically emulsified and coated on alumina ceramic tubes by dip coating. The microstructure and morphology of nanocomposites were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. The resistance and sensitivities to poisonous volatile organic compounds (PVOCS) were investigated on the static testing chamber. The XRD analysis of nanocomposites revealed the appearance of ZnWO₄ with a monoclinic structure in the whole concentration range (1–99 at.%). The FESEM results showed that as-prepared nanocomposites were composed of almost spherical particles with size range from 200 to 300 nm. Gas-sensing properties of Zn–W–O nanocomposites ceramics, to formaldehyde, benzene, and xylene, were detected. The results showed that the ZnWO₄ phase with high resistance almost did not respond to PVOCS. The appropriate amounts of ZnWO₄ in ZnO-rich samples and in WO₃-rich samples lend themselves to enhancement of gas-sensing properties to PVOCS. The effect of ZnO, WO₃, and ZnWO₄ with a scheelite structure as solid acidic/alkaline catalysts on gas-sensing property is also discussed.     

模具行业信息

<正>新兴战略性产业将牵引中国模具产业增长在当前"后危机时代",世界各主要发达国家和经济体均选择了不同的新兴产业作为突破口。奥巴马政府将新兴产业重点放在新能源和环保产业上,欧盟重在将"绿色技术"和其他高端技术提升至全球领先水平,日本把重点产业放在新型汽车、低碳产业、新能源(太阳能)等新兴产业,韩国将绿色技术、尖端产业融合、高附加值服务等三大领域共17项新兴产业确定为重点产业。尽管各国的政治经济体制不同,但无论是以市场经济为主导的欧美国家,还是以政府主导型经济为主的东亚国家和地区,政府大多对未来需要重点发展的新兴产业给予必要的培育和扶持。如今,中国政府已     

基于模板匹配的二维图自动生成算法研究

基于模板匹配的思想,对二维图的自动生成算法进行了研究。首先将模板和待标注三维模型的点、线、面信息以及几何结构和拓扑结构以属性图的数据结构方式进行存储,通过面的广度优先搜索和边的广度优先搜索对存储的2个属性图进行匹配,再读取模板二维图上的标注等信息,利用二维图和三维模型的关联性和属性图匹配结果,对待标注三维模型进行自动标注,包括尺寸标注、表面粗糙度标注、形位公差标注等信息。     

MA-SPS-HIP技术制备钒合金的工艺探索

探索了机械合金化-放电等离子体烧结-热等静压(MA-SPS-HIP)技术制备V-4Cr-4Ti-1.8YH2合金的工艺流程,并对其在1000~1200℃下真空退火后的性能进行了测试。XRD和SEM分析表明,球磨50 h以上基本上可以达到机械合金化的目的。材料的拉伸测试表明V-4Cr-4Ti-1.8YH2合金有良好的力学性能,并且在退火温度为1100℃真空退火后综合力学性能达到最佳。合金材料微观组织分析表明,V合金的晶粒尺寸大多在0.5μm以下,YH2在烧结过程中转变成了Y2O3,以小于50 nm的粒子弥散分布在基相之中。