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1.
Xue‐Yong Liu Xiao‐Bin Ding Zhao‐Hui Zheng Yu‐Xing Peng Albert S
C Chan C
W Yip Xin‐Ping Long 《Polymer International》2003,52(2):235-240
Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe3O4 magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g?1. © 2003 Society of Chemical Industry 相似文献
2.
选取具有代表性的碳钢、不锈钢、镀锌碳钢、铝、钛和铜挂片,在某企业不同部位投放后进行为期半年的大气腐蚀试验,得出了在半年期中的腐蚀规律。在此基础上,对每种金属材料的腐蚀特点进行总结,并对大气腐蚀的各种影响因素进行分析,提出了行之有效的防护措施。 相似文献
3.
María P. Albano Liliana B. Garrido 《Journal of Materials Synthesis and Processing》2002,10(4):211-218
Si3N4powders coated with 6 wt% Y2O3and 4 wt% Al2O3were prepared by coprecipitation. The resulting powders were dispersed in water at different pH values and with addition of various amounts of ammonium polyacrylate (NH4PA) to produce 32 vol% slips. The influence of the amount of NH4PA solution added and pH on the rheological properties of 32 vol% coated Si3N4slips were studied. In addition, the sintered density of cast samples was determined and related to the degree of slip dispersion. The adsorption of the NH4PA on the coated particle surface was rather high and the surface became saturated near 0.86 mg/m2at pH 9.2. High NH4PA concentrations (1.7–3 wt%) were necessary to obtain well dispersed 32 vol% coated Si3N4slips at pH 9.2. The best stabilization was obtained with the addition of 2.3 wt% NH4PA; in this condition, the viscosity reached a minimum value of 35 mPa.s at 100 s–1. The slip viscosity increased with increasing pH from 9.2 to 10.2. Slips with low viscosities gave a more dense packing of cast samples and consequently higher sintered density values. 相似文献
4.
The formation of aluminum matrix composites fabricated by exothermic dispersion reaction in A1-TiO2-B2O3 system was investigated. The thermal analysis results show that the reactions are spontaneous and exothermic. The Gibbs free energy of α-Al2O3 is the lowest among all the combustion products, followed by TiB2 and Al3Ti. It is noted that when the B2O3/TiO2 mole ratio is below 1, the reaction products are composed of particle-like α-Al2O3, TiB2 and rod-like Al3Ti. The α-Al2O3 crystallites, resulting from the reaction between A1 and TiO2 or B2O3, are segregated at the grain boundaries due to a lower wettability with the matrix. SEM micrographs show that rod-like Al3Ti phase distributes uniformly in the matrix. When the BEO3/TiO2 mole ratio is around 1, the Al3Ti phase almost disappears in the composites, and the distribution of α-Al2O3 particulates is improved evidently. 相似文献
5.
6.
胜利炼油厂重油加氢 (VRDS)装置的常压分馏塔为填料塔 ,2 0 0 1年检修开工后该系统出现异常 ,经过查找分析 ,确定轻烃 /产品减压渣油换热器和柴油汽提塔重沸器内漏是装置异常的主要原因 相似文献
7.
Huai Wen-xin Wuhan University of Hydraulic & Electric Engineering Wuhan Hubei P.R.China Prof.Li Wei 《水动力学研究与进展(B辑)》1993,(3)
Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion. 相似文献
8.
利用修正的非线性Schrodinger方程研究了单模光纤最小群速度色散波长附近的调制不稳定性,发现了一个新的由光纤四色散导致的调制不稳定性区域,该区域的调制范围与初始入射脉冲的功率和四阶色散有关。 相似文献
9.
G.652光纤上的2.5Gbit/s色散受限系统 总被引:1,自引:0,他引:1
本文根据色散受限中继段长度的计算,对实际工程中1550nm波长2.5Gbit/s系统进行计算比较得出啁啾声引起的色散不容忽视,它使2.5Gbit/s成为色散受限系统。对1310nm波长622Mbit/s系统,当使用多纵模激光器时,往往也会成为色散受限系统。 相似文献
10.
针对当前国内长途传输光缆系统在扩容过程中,因光信号色散而影响传输质量的现象,结合实际工程建设,分析了光信号色散的危害及其成因,并提出了相应的解决办法及建议。 相似文献