熔融石英陶瓷的性能及其应用

介绍了石英陶瓷的性能特点、制备过程及应用领域     

Glass Formation and Properties in the System Calcia-Gallia-Silica

The glass-formation region of the calcia-gallia-silica system was determined. The glasses within this region were measured to have a density of 3 to 4 g/cm³, a refractive index of 1.6 to 1.73, an Abbe number between 35 and 58, a thermal expansion coefficient of 6.5 × 10⁻⁷/°C to 11.5 × 10⁻⁷/°C, softening temperatures between 730° and 790°C, and a Vickers microhardness of 5.2 to 7.3 GPa. Crystalline phases were identified along the glass-formation boundary. Infrared transmission spectra were used to explain glass structures and their effect on glass properties. The results suggest that the role of calcia in the glass structure is similar to that for calcia in calcium aluminosilicate glasses.     

纳米材料及其在有机硅材料中的应用

简要介绍了纳米技术和纳米材料如粒径为10－30nm的石英粉、TiO2、ZnO、Fe2O3、CaCO3、气相法白炭黑等在有机硅材料中的应用。     

Biocidal hydantoinylsiloxane polymers. IV. N‐halamine siloxane‐functionalized silica gel

The monomer 5,5‐dimethyl‐3‐(3′‐triethoxysilylpropyl)hydantoin and its hydrolysis product polymer poly[3‐(5,5‐dimethylhydantoinylpropyl)hydroxysiloxane] were employed to functionalize the surfaces of silica gel particles in order to produce an adhered film that becomes biocidal upon chlorination with dilute sodium hypochlorite bleach. The biocidal efficacy of the functionalized silica gel was demonstrated in a cartridge filter experiment against the bacterial pathogens Staphylococcus aureus and Escherichia coli O157:H7. Complete 6 log inactivations of the two bacterial species were observed within 30 s of contact. Moreover, upon loss of biocidal activity due to depletion of bound chlorine, the coated silica gel particles could be recharged by further exposure to dilute bleach. Potential uses of the biocidal silica gel include disinfection and odor control in water treatment facilities and recirculating baths. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3448–3454, 2006     

Application of the Stepwise-Regression Method in Calculating High-Temperature Ceramic Phases

Phase calculation for nonequilibrium multicomponent systems is attempted using the stepwise-regression method. The experimental data (the amount and composition of glassy phase in a system of Al₂O₃–SiO₂ ceramics as functions of the state of the original materials, the firing temperature, and the composition of the samples) are treated by the proposed method. The equations obtained are accurate in estimating the amount and composition of glassy phases in the system, showing that the stepwise-regression method is effective in phase calculation.     

Investigations of Electrical Properties in Silica/Indium Tin Oxide Two-Layer Film for Effective Electromagnetic Shielding

The effect of zinc ions added to silica film on the electrical and structural properties of a silica/indium tin oxide two-layer film which had been prepared by solution coating for electromagnetic shielding of displays was studied. The volume resistivity of the undoped silica/indium tin oxide film was more than 3 times as high as that of the zinc-doped silica/indium tin oxide film. The addition of divalent cations, zinc ions, to the overcoated layer led volume resistivity of the two-layer film to decrease significantly and also caused a long-term increase in stability. The decrease in volume resistivity was due to the addition of zinc ions that changed the interface ionization and helped to enhance the electrical conductivity in the two-layer film.     

中孔二氧化硅薄膜的仿生制备技术

以薄膜的形式仿生制备二氧化硅中孔材料于1996年首次报道，最后，在其制备方法得以改进、分析和表征技术得以提高的基础上，所制备出的中孔薄膜不但具有很好的几何孔型，而且孔道有序排列的方向及膜的厚度均可在合成过程中进行调控，通过仿生制膜技术裁剪无机中孔膜的各种特性，可使它们广泛应用于对中相形态控制要求严格的催化及微电子领域。     

Influence of operation parameters on the separation of mixtures by pervaporation and vapor permeation with inorganic membranes. Part 1: Dehydration of solvents

The separation performance of two different commercially available tubular inorganic membranes was studied for solvent dehydration. The separation layers consisted of A-type zeolite and microporous silica. The membrane characteristics were determined as function of operating conditions such as feed composition, temperature, and permeate pressure in pervaporation and vapor permeation. Among different membranes of the same batch, flux and selectivity were reproducible within 10%. The partial flux of water as the preferentially permeating component increases linearly with the water vapor pressure difference between feed and permeate and depends only marginally (viscosity influence) upon the properties of the organic component. The flux of the organic (retained) component is low and can best be described by assuming a substance and membrane specific permeance (flux over partial pressure difference) that is independent of composition. At very low water concentration in the feed one would expect a strong increase in permeability of the retained component through non-zeolite pores and larger silica pores as predicted by pure component measurements. However, this effect was not observed in mixtures within the concentration range studied here. A temperature rise improves flux rates exponentially while selectivity remains high. Thus, higher module cost in comparison to polymeric membranes can be compensated by reduced membrane area if a higher operating temperature can be chosen. Flux and selectivity decline as a function of permeate pressure with decreasing driving force. In vapor permeation with inorganic membranes superheating of the vaporous feed improves their performance while for polymeric materials a steep flux decline is observed. High flux and selectivity are obtained in the separation of water from alcohols. The normalized flux values of the A-type zeolite membrane are roughly 10 kg/m² h bar with a mixture selectivity of 2000 for methanol, 4000 for ethanol and 8000 for n-butanol. The average permeance of the amorphous silica membrane lies above 12 kg/m² h bar with mixture selectivity of 50 for methanol, 500 for ethanol and 2000 for n-butanol. The separation mechanism is mainly based on adsorption and diffusion enhanced by shape selectivity and size exclusion in some cases. The transport characteristics could be described with a simple transport model based on normalized permeate fluxes. With regard to the operation stability of the membranes, no deterioration of the performance was observed for the A-type zeolite in solvent dehydration or in separation of water from reaction mixtures. The silica membrane showed an initial conditioning effect involving a rearrangement of Si-OH groups with an increase in selectivity and decrease in flux of about 30%. After a few hours the performance stabilized and remained constant during further operation.     

纳米SiO_2改性外墙涂料的研究

介绍了纳米材料改性高性能建筑外墙涂料的配方及研制,着重讨论了纳米SiO2添加量对涂料性能的影响:掺入4%的纳米SiO2能明显改善涂膜的附着力、光泽度、耐水、耐碱、耐洗刷性和涂料的抗沾污性、触变性能、稳定性。     

以硅胶为载体的茂金属催化剂研究进展

综述了近年来硅胶载体经甲基铝氧烷(MAO)化学处理后负载茂金属催化剂的一些研究进展，指出硅胶的化学活化是茂金属催化剂负载化的关键，单组分化学处理剂处理硅胶载体不能完全满足人们对负载型茂金属催化剂烯烃聚合的需求，采用含MAO的多组分化学处理剂化学活化硅胶后负载催化剂是该领域发展的趋势。