Ti－24Al－11Nb金属间化合物的氢致滞后开裂

Ｔｉ－２４Ａｌ－１１Ｎｂ金属间化合物的氢致滞后开裂张跃，王忆，王燕斌，褚武扬，肖纪美（北京科技大学北京１０００８３）１引言复相金属间化合物Ｔｉ－２４ＡＬｌｌＮｂ合金是一种重要的新型高温结构材料，已被美国宇航局用作为新一代宇航飞机的发动机材料及结构件．...     

PRESSURE DISTRIBUTION IN THE AIR-SPARGED HYDROCYCLONE

ＰＲＥＳＳＵＲＥＤＩＳＴＲＩＢＵＴＩＯＮＩＮＴＨＥＡＩＲ－ＳＰＡＲＧＥＤＨＹＤＲＯＣＹＣＬＯＮＥ￥Ｃｈｕ，Ｌｉａｎｇｙｉｎ；ＬｕｏＱｉａｎ（ＭｉｎｅｒａｌＥｎｇｉｎｅｅｒｉｎｇＤｅｐａｒｔｍｅｎｔ，ＮｏｒｔｈｅａｓｔｅｒｎＵｎｉｖｅｒｓｉｔｙ，Ｓｈｅ...     

大型离心复合球墨铸铁轧辊的生产

简述了我公司为舞阳铜厂试制４２００ｍｍ厚板轧机离心复合球墨铸铁轧辊的性能要求、内外层双重金属铸造工艺参数的选择及整个铸造生产工艺过程。     

紫杉醇聚合物胶束载药体系的研究进展

紫杉醇（paclitaxel,PTX）是一种常用的抗肿瘤药物,但其极差的水溶性限制了其在临床上的应用。为使其能更好的为人体所利用,近年来,研究者们开发了多种紫杉醇载药体系,其中聚合物胶束载药体系以其特有的优点为目前研究的热点,并具有广阔的发展前景。介绍了近年来采用两亲嵌段共聚物制备紫杉醇聚合物给药体系的研究进展。展望了该体系今后的发展方向。     

固液体系中锌离子的动态吸附过程及去除率

在离子浓度50～200 mg/L和蛭石介质浓度50～150 g/L范围内分析测试了固液体系中Zn2 离子的吸附速率.结果表明,蛭石具有较强吸附Zn2 的能力,其吸附速率在初始2h内很高,但随时间的延长逐步降低,并在8 h左右趋于零.溶液起始Zn2 浓度和吸附剂浓度对吸附速率有显著影响,随起始Zn2 浓度增大,吸附达到平衡的时间延长;起始吸附剂浓度越大,吸附平衡时间越短.本文提出的蛭石吸附Zn2 的动态方程在样品检测的浓度范围内具有较高的模拟精确度.中试监测结果表明,人工湿地系统中的蛭石吸附单元可有效去除实验室废水中的锌与其它有毒污染物质.     

Influence of different modified β zeolite on skeletal isomerization of n-hexene in the presence of hydrogen

Zeolite β was modified via treating with oxalic acid and doping with magnesium, and the influence of different modified zeolite β on skeletal isomerization of n-hexene in the presence of hydrogen was investigated. Moreover, parent β and modified β were characterized by XRD, N₂ physisorption, IR, NH₃–TPD, ²⁷Al MAS NMR and ²⁹Si MAS NMR, respectively. The results indicated, compared with parent β, β treated by oxalic acid was found that non-framework aluminum was removed effectively, and surface aluminum and framework aluminum were eliminated partly, which resulted in considerable decrease in the amount of acid sites. In contrast, the introduction of magnesium has little effect on crystalline structure of β, but it can reduce the amount of strong Brönsted acid sites. Noticeably, when β was modified by the combination of oxalic acid treatment and Mg dope, it can not only remove non-framework aluminum and reduce the amount of acid sites, but also facilitate the stability of crystalline structure of β and further eliminate strong Brönsted acid sites due to the introduction of Mg. The evaluation results of skeletal isomerization of n-hexene in the presence of hydrogen showed that, compared with parent β, β modified by the combination of oxalic acid treatment and Mg dope exhibits better activity and stability.     

Surface modification and metallization of polyimide using gold colloids as a seed layer

Herein we report on metallization of Cu on to surface‐modified polyimide resin, the method of which relies on potassium hydroxide‐induced modification of the polyimide surface to introduce carboxylic acid groups and incorporation of gold colloids as a seed layer through reduction of chloroauric acid. The contact angle of modified polyimide surface with water changed from 70 to 35° due to the hydrolysis of polyimide. Secondary amine group on the surface was detected with attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectrophotometry, suggesting that tertiary amine group has turned into secondary group. In addition, on the basis of hydrophilic behavior, we succeeded in depositing gold colloids on the chemically modified surface. SEM image of copper electroless plated on polyimide surface indicated that copper particles were compact and about ～ 300 nm in diameter. It showed that gold colloids provide an excellent conductive layer to catalyze the electroless plating of Cu on polyimide surface. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study of a novel halogen‐free flame retardant system through TGA and structure analysis of polymers

Butadiene‐rubber toughened styrene polymers, such as acrylonitrile‐butadiene‐styrene (ABS) copolymer and high impact polystyrene (HIPS), are noncharring polymers. They are generally blended with polycarbonate (PC) or polyphenyleneether (PPE), which are char forming polymers, to improve char forming ability for styrenic blends containing conventional phosphate flame retardants. To achieve cost effective flame retardant system, PET was selected as a potential char‐source for ABS blends through the thermogravimetric analysis (TGA) and chemical structure analysis of various polymers. PET may contribute to the enhancement of flame retardancy of ABS/PET blends, especially in the presence of small amounts of phenol novolac (PN). The effective flame retardancy of this system is believed to be accomplished through the enhancement of interchain reactions by PN. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Spray deposited fluoropolymer/multi-walled carbon nanotube composite films with high dielectric permittivity at low percolation threshold

High performance perfluoro alkoxy (PFA) and chemical vapor deposition-grown multi-walled carbon nanotube (MWCNT) composite films with thicknesses of 30 μm were prepared using a scalable spray deposition technique. A homogeneous distribution of MWCNTs within the PFA matrix was confirmed by electron and optical microscopy. Dielectric and AC conductivity measurements showed a significant enhancement of dielectric permittivity for PFA/MWCNT films at low frequencies, and a very weak dependence of dielectric permittivity on temperature in the range 25-230 °C. Very low percolation threshold volume fractions of ca. 0.0043 and 0.0017 were attained for MWCNTs with two different aspect ratios, which have been explained by an inherent feature of spray route, a microcapacitor model and percolation theory. The combination of PFA/MWCNT composites and the spray deposition route provides a promising approach for the fabrication of industrial scale composite films with well-controlled dielectric properties for micro-electronic and high temperature applications.     

Functionalization of fullerene nanowhiskers using pyrenebutanoic acid, succinimidyl ester in an aqueous solution

The functionalization of fullerene nanowhiskers was accomplished by non-covalent π-π interaction using pyrenebutanoic acid, succinimidyl ester to immobilize target molecules on the nanowhiskers. Fourier-transform infrared spectroscopy and fluorescence microscopy proved that the fullerene nanowhiskers were functionalized without damaging the nanostructure.