铁电极氰化物电镀过程中的活化现象

采用循环伏安法和恒电流法研究了铁电极在氰化物电解液中的行为,证实了在阴极过程中电极首先极化至铁表面钝态层的还原,实现了表面的活化;随后极化至金属在活化的铁基体上的电沉积过程。     

偶联剂对地砖用PVC填充材料相态结构和力学性能的影响

研究了钛酸酯类偶联剂和硅烷类偶联剂对钙矿、硅酸盐填充的PVC填允材料力学性能、相态结构、密度、热失重率及吸水伸长率和耐热阻燃性能的影响。结果表明,偶联剂可改善填充PVC的抗冲性能,降低其拉伸强度,扫描电镜分析表明,填料越细,分散越均匀,越易被PVC树脂所包覆,力学性能越好,研究得到了比重大、热失重率低、吸水伸长率小、阻燃耐烧灼性好的高填充PVC硬质塑料地板砖。     

Benzene Alkylation with Propane over Mo Modified HZSM-5

Benzene alkylation with propane has been studied over HZSM-5 loading 3.1–15.4 wt% Mo in continuous-flow microreactor under 350 °C and atmospheric pressure with the highest activity obtained at 6.7 wt% Mo loading. C_7–9 aromatics were obtained as main products while the total amount of benzene rings kept unchanged. i-Propylbenzene and n-propylbenzene are formed primarily, while toluene, ethylbenzene, and ethyl-toluene are formed secondly from the propylbenzenes. Catalytic performance of 6.7 wt% Mo/HZSM-5(38) partially poisoned by NH₃ shows that the strong acid sites play a crucial role in the alkylation. Low SiO₂/Al₂O₃ ratio of HZSM-5 in the Mo modified catalysts gives high propane conversion. Two hydrothermal treatment methods were applied to the 6.7 wt% Mo/HZSM-5(38) catalyst, caused decrease of propane conversion but result in different product distribution. A possible reaction mechanism concerning bifunctional active centers resulted from combination of loaded Mo species and strong acid centers on HZSM-5 is proposed.     

γ-Y2Si2O7, a Machinable Silicate Ceramic: Mechanical Properties and Machinability

In this paper, the mechanical properties of bulk single-phase γ-Y₂Si₂O₇ ceramic are reported. γ-Y₂Si₂O₇ exhibits low shear modulus, excellent damage tolerance, and thus has a good machinability ready for metal working tools. To understand the underlying mechanism of machinability, drilling test, Hertzian contact test, and density functional theory (DFT) calculation are employed. Hertzian contact test demonstrates that γ-Y₂Si₂O₇ is a "quasi-plastic" ceramic and the intrinsically weak interfaces contribute to its machinability. Crystal structure characteristics and DFT calculations of γ-Y₂Si₂O₇ suggest that some weakly bonded planes, which involve Y–O bonds that can be easily broken, are the sources of the low shear deformation resistance and good machinability.     

我国硫磺和硫铁矿制酸大型装置综述(续完)

硫磺制酸的发展与硫铁矿制酸的发展有所不同，没有象大型硫铁矿制酸通过引进国外的先进技术而发展起来的，而是通过消化吸收引进的硫铁矿制酸技术或设备，完全依靠自己的能力发展起来的。我国硫磺制酸起步晚，但发展十分迅速。装置的大型化是从上世纪90年代中期开始发展的，装置规模从200kt／a、300kt／a起，逐步积累经验，直到800kt／a的建设。随着硫酸生产新技术、新装备的不断开发、应用，我国大型硫磺制酸装置的设计、施工、管理正日趋成熟。     

原位合成TiB2-TiCx复相陶瓷的显微组织

应用光学显微镜(OM)、X射线衍射(XRD)、透射电镜(TEM)和扫描电镜(SEM)对原位合成的TiB2-TiCx复相陶瓷显微结构进行了分析。并分析了Ti-B4C反应的原位生成机理。结果表明,Ti3B4相稳定存在于生成物中,其形态与形成温度和反应机理有关。     

Water sorption of poly(vinyl alcohol)/ poly(diallyldimethylammonium chloride) interpenetrating polymer network hydrogels

Temperature‐responsive interpenetrating polymer network (IPN) hydrogels constructed with poly(vinyl alcohol) and poly(diallyldimethylammonium chloride) using the sequential IPN method were studied. The characteristics of IPN hydrogels were investigated using the dynamic vapor sorption system. IPN hydrogels exhibited a relatively high sorption ratio, 180–360% at room temperature. The sorption ratio of hydrogels depended on temperature. Diffusion coefficients were calculated according to the Fickian Law at several temperatures. The apparent activation energy was 5.43 kJ mol^?1, which corresponds to typical diffusion processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1389–1392, 2003     

Characteristics of electrical responsive chitosan/polyallylamine interpenetrating polymer network hydrogel

An interpenetrating polymer network (IPN) hydrogel composed of chitosan and polyallylamine exhibited electric‐sensitive behavior. The chitosan/polyallylamine IPN hydrogel was synthesized by radical polymerization using 2,2‐dimethoxy‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The swelling behavior of the IPN was studied by immersion of the gel samples in aqueous NaCl solutions at various concentrations and pHs. The swelling ratio decreased with increasing concentration and pH of electrolyte solution. The stimuli response of the IPN hydrogel in electric fields was also investigated. When a swollen the IPN was placed between a pair of electrodes, the IPN exhibited bending behavior in response to the applied electric field. The IPN also showed stepwise bending behavior depending on the electric stimulus. In addition, thermal properties of the IPN were investigated by differential scanning calorimetry (DSC) and dielectric analysis (DEA). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2290–2295, 2002     

气相法合成纳米颗粒的制备技术进展

本文综述了气相法合成纳米颗粒材料的主要制备技术，并介绍了制备方法的最新进展－化学气相冷凝技术制备纳米颗粒材料，提出了制备纳米颗粒技术研究中面临的问题及今后的发展方向。