NH_4Cl水溶液在成膜过程中的致孔作用

本文以ＮＨ４Ｃｌ饱和水溶液做添加剂，对ＰＶＤＦ／ＮＭＰ体系在成膜过程中的致孔作用做了研究。铸膜液中随ＮＨ４Ｃｌ水溶液加入量的改变，膜孔径也发生变化，并出现最大值。通过Ｘ－射线衍射扫描发现制膜液中存在无机盐时膜中无定形态结构增加，表明无机盐的加入有助于膜孔形成     

Characteristic Investigation of Nano-Crystal Hydrogen Storage Alloys

A Ml (NiCoMnA1)5 hydrogen storage alloys was prepared by double-roller rapid quenching.Its microstructure, electrochemically and kinetic characteristic were studied.A uniform crystal phase with CaCu5 structure could be detected by XRD analyses, whose average grain size is 30 ～ 50 nm and the ratio of c/a of nano-crystal hydrogen storage alloy is larger.The hydrogen absorption/desertion p - C isotherms of alloy show that its fiat-performance is perfect and the magnetic stagnant effect is very little.An simulate cell is used for electrochemical measurement.Electrode is 10C, the capacity decreasing rate via the 450 cycles at 7C is less than 20%.     

草酸二甲酯加氢合成乙二醇反应的研究

在微型管式反应器中,采用Cu/SiO2催化剂,在温度190～210℃、压力1～3MPa、草酸二甲酯(DMO)与氢气的摩尔比(氢酯比)40～120、DMO空速6.0～25.0mmol/(g.h)的条件下,对DMO加氢制乙二醇的反应进行了研究。实验结果表明,高温、高压、高氢酯比和低DMO空速都能提高DMO的转化率和乙二醇的收率,但同时也增加了副产物的选择性。较适合的反应条件为:压力2MPa,温度205～210℃,氢酯比80～100,DMO空速10.0mmol/(g.h)。动力学研究表明,DMO加氢反应符合Langmuir-Hinshelwood吸附反应动力学模型,表面反应为速率控制步骤,氢气不解离吸附,由此得到了相应的动力学方程及参数。统计检验结果表明,该模型对DMO加氢反应高度适定。     

EFFECT OF TRACE ADDITIVE ON ANTI-OXIDATION OF MOLTEN Sn-Pb EUTECTICS

以撇取氧化膜称重的方法对比了周期表中25个常见元素对Sn-Pb共晶合金抗氧化能力的影响。其中以Ga,Ge,P的能力最强。最佳含量(wt-％)分别为Ga0.0008,Ge0.004,P0.003。用对氧化渣的化学分析法、X射线衍射法以及合金表层的X射线光电子能谱法研究了Ga,Ge,P三元素对Sn-Pb合金的抗氧化机理。实验表明,添加的微量元素均在表层高度富集,厚度30—40(A),Ga则深达70-100(A),它们形成致密的保护膜。膜的成分是相应添加元素的氧化物与氧化锡形成的复杂含氧酸盐。温度对含P和Ge的合金影响较大,高于350℃则失去其抗氧化能力。含Ga的合金在400℃范围内一直是稳定的。     

THE MODIFICATION OF Si PHASE IN Al-Si EUTECTIC ALLOYS——Effect of Element Addition on Microstructures of Al-Si and Al-Si-Ge Eutectic Alloys

用金相方法考察了微量添加元素对Al-Ge和Al-Si-Ge共晶合金显微结构的影响。ⅡB,ⅢA,ⅣA和ⅤA族元素对Al-Ge共晶结构并无影响;ⅣB,ⅤB和ⅥB族难熔金属影响较大,共晶Ge聚集为大块的结晶;碱金属,碱土金属和一些VⅢ族金属的加入,使Al-Ge共晶点向富Al方向移动。Al-Ge共晶不出现类似Al-Si共晶的那种变质现象.Al-Si-Ge系变质时,Si以变质的共晶团存在。根据Al-Ge和Al-Si结晶过程的对比,认为Al-Si共晶的变质,主要取决于变质剂原子对(100)_(Al)∥(110)_(Si)外延关系的影响。     

SELECTION OF FILLER METAL FOR ALUMINUM BRAZING AND ITS REACTION WITH BASE METAL

考察了28种有代表性的微量元素对Al-Si共晶钎料的熔点,流动性,抗腐蚀性以及钎缝折弯能力的影响。其中以Al-Si(13.0)-Be(0.4—0.8)-Sr(0.03—0.06)-La(0.03—0.06)钎料体系最为理想。本文还探讨了钎料对母材熔蚀的机理,分析了钎焊温度和钎料组成的影响,此外,还认为与母材熔入钎料的速度以及液态钎料沿钎缝的流布速度有关,此二速度的比值愈大,熔蚀愈烈。最后,在钎焊温度下对钎缝进行了不同时间的保温处理,发现钎缝的强度和抗弯能力仅有不大程度的改善。     

MACROPROCESS OF PARTICLE FORMATION IN SUSPENSION POLYMERIZATION OF STYRENE WITH INORGANIC STABILIZER SYSTEM

The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used.Those items such as the effects of the Weight fraction of dispersed-phase,the amount of the inorganic stabilizer and the agitation speed on the breakup and coalescence of thetransient dispersed drops etc.Were examined.Results showd that the dynamic behavior of the transi-ent polymer droplets changed in the presence of the suspension stabilizer during the reaction.     

Fabrication of polysulfone asymmetric hollow‐fiber membranes by coextrusion through a triple‐orifice spinneret

Polysulfone (PSf) asymmetric hollow‐fiber membranes, which have a dense outer layer but a loose inner layer, were tentatively fabricated by coextrusion through a triple‐orifice spinneret and a dry/wet‐phase inversion process. Two simple polymer dopes were tailored, respectively, for the dense outer layer and the porous inner layer according to the principles of the phase‐inversion process. By adjusting the ratio of the inner/outer extrusion rate, the hollow‐fiber membranes with various thicknesses of outer layers were achieved. The morphology of the hollow‐fiber membranes was exhibited and the processing conditions and the water permeability of the membrane were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 259–266, 2004     

多腔钢管混凝土分叉柱力学性能有限元分析

为研究异形截面多腔钢管混凝土分叉柱的力学性能及设计方法,以北京某超高层建筑异形截面多腔钢管混凝土巨型分叉柱为原型,在已进行的低周反复荷载试验基础上,对异形截面多腔钢管混凝土分叉柱抗震性能进行有限元分析,研究了不同构造措施、不同钢材及混凝土强度等级等参数对钢管混凝土分叉柱抗震性能的影响.结果表明:基于本文提出的有限元建模方法,所得有限元分析结果与试验结果吻合较好;适当增加腔体数,设置肋板、角钢和钢管能够有效提高异形截面钢管混凝土分叉柱抗震性能;在等用钢量下,增加腔体数量比增加钢板厚度能更有效地提高分叉柱抗震性能;不同材料强度对异形截面钢管混凝土分叉柱抗震性能有较大影响,在进行其抗震设计时,宜选用强度等级匹配的钢材与混凝土.