硅溶胶对建筑石膏性能的影响

对添加了硅溶胶的建筑石膏进行研究,测定了这种胶凝材料的物理—力学性能。结果表明,硅溶胶可作为石膏材料的增强剂。     

Deterioration and Recovery of Metakaolin Blended Concrete Subjected to High Temperature

The deterioration and spalling frequency of metakaolin (MK) blended concrete subjected to high temperature is analyzed and compared with the equivalent silica fume (SF), fly ash (FA) and pure OPC concretes. Normal and high strength concrete mixes incorporating 0–20% MK were prepared and exposed to a series of high temperatures till 800°C. The residual compressive strength, porosity and pore size distribution were determined. It was found that after an increase in compressive strength at 200°C, the MK concrete suffered a more severe loss of compressive strength and permeability-related durability than the corresponding SF, FA, and pure OPC concretes at higher temperatures. Explosive spalling was observed in both normal and high strength MK concretes, and the frequency increased with higher MK contents. It is concluded that the dense micro-structure and low porosity are the main reasons of the poor performance of MK concrete at high temperature. The effect of post-fire curing on the strength and durability recovery of fire-damaged concrete was also investigated. The test results indicated that the post-fire curing, results in substantial strength and durability recovery, and its extent depends upon the types of concrete, exposure temperature, method, and duration of re-curing.     

体相与表面缺陷对石英玻璃腐蚀形貌的影响

系统研究四类石英玻璃受HF酸腐蚀后的表面形貌,以及不同加工方法对其腐蚀表面质量的影响。结果表明,Ⅰ类石英玻璃体相结构中含有大量气泡、颗粒、条纹缺陷,导致其腐蚀表面质量差。Ⅲ、Ⅳ类玻璃体相结构缺陷少,腐蚀表面质量明显优于Ⅰ、Ⅱ类玻璃,切、研、抛加工过程中产生的表面缺陷是其腐蚀表面形貌的主要影响因素。     

水性树脂体系中二氧化硅消光剂的评价及应用

在几个水性树脂体系中,对典型的气相二氧化硅消光剂和沉淀法二氧化硅消光剂的消光性能进行了评价实验,结合物性分析和消光原理对实验结果和二氧化硅消光剂的应用技术进行了探讨,结论对于二氧化硅消光剂的选择和应用具有指导意义。     

余姚临海浦闸的除险加固处理

介绍处于潮位变化区的海闸下游出口处连拱式挡土墙的除险加固工程。施工时根据现场情况，对水位变化区、潮湿部位、上部干燥部位及前后墙开裂部位，分别采用PBM混凝土、硅粉混凝土、982锚固剂及丙乳混凝土进行处理，达到预期的效果。     

Increasing the dissolution rate of a low-solubility drug through a crystalline-amorphous transition: a case study with indomethacin [correction of indomethicin

The purpose of this research is to further the understanding of the crystalline to amorphous phase transition (amorphization) that occurs when some crystalline drugs are dry blended with porous adsorbents. Indomethacin (IMC) and three grades of silica gel (SGs) were used in the study. Amorphization of crystalline IMC occurs rapidly during dry mixing with SG and was independent of mixing intensity and time. Extent of amorphization increases with lower ratios of IMC:SG and with decreased IMC and SG particle size. Blocking H-bonding silanol groups on SG by chemical modification reduced the extent of amorphization. IMC-SG mixtures showed improved dissolution rates over crystalline IMC, the improvement being directly related to the extent of amorphization. To preserve the improved dissolution rate, mixtures should be protected from moisture and heat. This approach holds promise as a mean of improving the dissolution rate of sparingly soluble drugs such as IMC.     

溶胶-凝胶法改性SiO2膜的润湿性与水汽稳定性

以甲基三乙氧基硅烷(MTES)替代部分正硅酸乙酯(TEOS)作为前驱物,用溶胶-凝胶法制备了MTES改性二氧化硅溶胶和二氧化硅膜,研究了憎水基团的添加量对溶胶体系的稳定性和对二氧化硅膜润湿性以及水汽稳定性的影响.结果表明,随MTES/TEOS摩尔比增大,二氧化硅溶胶的稳定性降低,改性二氧化硅膜的表面自由能显著减小;表面润湿性降低,主要是表面张力中极性力的贡献,FTIR分析表明,这是由于二氧化硅颗粒表面-CH3非极性基团增加所致;在潮湿环境中陈化时,二氧化硅膜接触角的变化及吸水率随MTES/TEOS摩尔比增大而减小,疏水性二氧化硅膜的MTES/TEOS宜为0.8～1.0;AFM形貌分析表明陶瓷支撑体上的二氧化硅薄膜连续,膜表面较光滑、平整.     

纳米沉淀二氧化硅的硅烷偶联剂原位表面改性

在沉淀二氧化硅的制备过程中,表面活性剂可以起到提高粒子分散性的作用.通过在沉淀二氧化硅制备过程中加入硅烷偶联剂,研究了硅烷偶联剂原位表面改性对沉淀二氧化硅性质的影响,并通过SEM、FTIR等分析手段对改性机理进行了分析.结果表明,当硅烷偶联剂(牌号为SCA-1613)的用量达到沉淀二氧化硅质量的6.0%时,制备得到的沉淀二氧化硅的物化指标明显改善.制得的样品白度97.1,比表面积223m2/g,吸油率为2.42ml/g,堆积密度为0.23g/ml.对改性前后的样品的SEM和FTIR分析表明,制得的沉淀二氧化硅原级粒度为纳米级,经过原位改性处理后,其团聚现象明显改善.FTIR分析表明,用硅烷偶联剂SCA-1613对沉淀二氧化硅在制备过程中进行表面改性时,改性剂分子吸附在二氧化硅颗粒的表面并与其形成化学键合.