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991.
Lianwei Shan Wei Li Rui Fang Zhidong Han Huanyan Xu Limin Dong Ze Wu Xianyou Zhang 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(4):855-860
Strontium barium niobate/strontium barium titanate (SBT) composite ceramics with different Nb/Ti ratios, [y(Sr0.3, Ba0.7)Nb2O6/(1 ? y)(Sr0.3, Ba0.7)TiO3], were fabricated using a Powder–Sol (P–S) method by suspending Nb2O5 powders in the sol solution of SBT. The microstructure of composite ceramics was characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Homogeneous and fine-grained composite ceramics were successfully prepared by P–S method. Tetragonal tungsten bronze phase and perovskite phase were revealed co-present in the composite ceramics, whose phase structure was dependent on the pre-sintering temperature and Nb/Ti ratios. The substitution reactions were proposed to explain the formation mechanism of the composite ceramics. 相似文献
992.
993.
通过分析不同硝酸铵含量的发射药的能量示性数,在φ30 mm火炮装填条件下,采用传统的经典内弹道模型,模拟计算出不同硝酸铵含量的七孔火药发射药的膛压、弹丸初速等弹道参数,研究硝酸铵含量对硝酸铵发射药内弹道参数的影响。结果表明,随着硝酸铵含量的增加,膛内压力和弹丸速度先增加后降低,硝酸铵含量存在一个最优点使二者达到最大值。 相似文献
994.
针对油井在生产过程中的出砂问题,选取了一种双酚A型环氧树脂ER1用于化学固砂实验,研究了其化学式及主要反应机理。并在室内测试了ER1固砂体系的性能。结果表明.在60℃下选用40~80目干燥石英砂、固化剂GN加量为1.2%、ER1树脂加量为4.5%、偶联剂KH550加量为0.2%、固化时间为24h的条件下,散砂固结体的抗压强度为12.3MPa。空气渗透率为12.9md.煤油渗透率为4.1md。固结体样品能够抵抗地层水、泥质等的混入。有较好的耐酸碱等介质的能力,在大流量长时间水的冲刷下没有散砂被冲出。 相似文献
995.
996.
以提取青蒿素后黄花蒿残渣为原料,采用超声醇提总黄酮。通过单因素实验方法和正交实验方法确定了最佳提取工艺条件;同时也考察所得黄酮纯化物对油脂的抗氧化性能,并与抗坏血酸、柠檬酸的抗氧化性进行了比较。结果表明:黄花蒿残渣中总黄酮超声辅助提取的最佳提取工艺为:按料液比1∶30 (g:mL)加入体积分数50%的乙醇,在55℃条件下用200 W超声辅助提取40 min,黄花蒿残渣中总黄酮提取率可达到9.10%。该黄酮纯化物对羟基自由基具有清除能力,随浓度的增大而升高;黄酮纯化物对油脂有明显的抗氧化性作用;对植物油的抗氧化能力强于抗坏血酸和柠檬酸;对动物油脂的抗氧化能力稍弱于抗坏血酸而略强于柠檬酸 相似文献
997.
TiO2 particles supported on multi-walled carbon nanotubes (MWCNTs) were prepared using a sol–gel method to investigate their photocatalytic activity under simulated solar irradiation for the degradation of methyl orange (MO) in aqueous solution. The prepared composites were analyzed using XRD, SEM, EDS and UV–vis absorption spectroscopy. The results of this study indicated that there was little difference in the shape and structure of MWCNTs/TiO2 composite and pure TiO2 particles. The composite exhibited enhanced absorption properties in the visible light range compared to pure TiO2. The degradation of MO by MWCNTs/TiO2 composite photocatalysts was investigated under irradiation with simulated solar light. The results of this study indicated that MWCNTs played a significant role in improving photocatalytic performance. Different amounts of MWCNTs had different effects on photodegradation efficiency, and the most efficient MO photodegradation was observed for a 2% MWCNT/TiO2 mass ratio. Photocatalytic reaction kinetics were described using the Langmuir–Hinshelwood (L–H) model. The photocatalyst was reused for eight cycles, and it retained over 95.2% photocatalytic degradation efficiency. Possible decomposition mechanisms were also discussed. The results of this study indicated that photocatalytic reactions with TiO2 particles supported on MWCNTs under simulated solar light irradiation are feasible and effective for degrading organic dye pollutants. 相似文献
998.
999.
Near-net-shaped hierarchical structure-adjustable short mullite fibers/mullite whiskers frameworks (MF/MW frameworks) were prepared by slurry-filtration and heat-treating method. The main structure of MF/MW framework was constituted by lap-jointed mullite fibers. Every single fiber in the framework was densely covered by mullite whiskers which formed through fluorine-catalyzed gas-phase reaction, and the fibers actually served as curved substrates for the mullite whiskers' growth. The lap-jointing points of the fibers were served by movable intersected mullite whiskers. Moreover, the microstructure of the frameworks could be adjusted by tailoring the raw materials mass ratio. The volume densities, the apparent porosities and the thermal conductivities of the MF/MW frameworks in different raw materials mass ratios were 0.459–0.487 g/cm3, 79.7–82.8% and 0.1356–0.1965 W/k m, respectively. The compression–resilience property of the samples was tested under 0.4 MPa at room temperature. The compression ratio and resilience ratio of the MF/MW frameworks in different raw materials mass ratios were 1.63–2.25% and 92.67–98.16%, respectively. The MF/MW frameworks with advanced thermal and mechanical properties were considered to be promising high-temperature heat-insulation material. 相似文献
1000.
Influence of atomizer exit area ratio on the breakup morphology of coaxial air and round water jets
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Hui Zhao Hai‐Feng Liu Xiu‐Shan Tian Jian‐Liang Xu Wei‐Feng Li Kuang‐Fei Lin 《American Institute of Chemical Engineers》2014,60(6):2335-2345
The goal of this article is to study the effect of atomizer exit area ratio on atomizer performance. The experiments are performed on the round liquid jet breakup of seven coaxial air‐blast atomizers with water–air systems. The breakup morphology of liquid jet is observed first. The membrane‐type breakup can be divided into two subregimes called bag‐type breakup and membrane‐fiber breakup, and a correlation of characteristic length on bag‐type breakup regime is obtained. Then, we analyze the influence of atomizer exit area ratio on the breakup morphology of water‐air jets. To obtain reasonable atomization morphology criterions, the atomizer exit area ratio is used to modify the Weber number and momentum flux ratio per unit volume. This method is found to be able to explain different experimental results in the literature, which is also close to the results of round liquid jet in cross air flow and secondary atomization. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2335–2345, 2014 相似文献