Preparation and crystallization action of SiO2 -Al2O3 -CaO-ZnO-R2O porous glass-ceramics

Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.     

基于废弃物利用的自保温墙体配套砂浆制备及性能研究

采用淤泥陶砂、废弃加气混凝土结合传热系数小的玻化微珠为砂浆骨料,基于"复合化"思想,制备自保温墙体配套砂浆。采用正交实验探讨混掺砂浆的合理配比,控制4项参数:胶凝材料用量、陶砂(或废料)与玻化微珠体积比、硅灰取代量和胶粉掺量,以干容重、抗压强度、导热系数为考核指标,制备综合利废效果最佳的新型混掺复合保温砂浆。结果表明,陶砂玻化微珠复合砂浆导热系数0.16～0.29W/(m.K),随着陶玻比增大而增大,因此陶砂体积含量增加有利于提高保温性能,加气废料玻化微珠复合砂浆的导热系数0.10～1.14W/(m.K),与陶砂复合保温砂浆相比,有较大的降低。     

凹凸棒石粘土提纯技术及性能研究

添加分散剂对凹凸棒粘上进行提纯,提高凹凸棒粘上的纯度,改善其分散性。通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)观察其显微结构,并用X射线(XRD)分析提纯杂质,与原土和采用纯水机械搅拌提纯的凹凸棒粘上进行对比实验。实验结果表明,与凹凸棒原土及纯水法纯化的凹凸棒土相比,添加分散剂的提纯效果最好,提纯后杂质明显减少,应用在建筑材料等方面有广阔的前途。     

磁化水混凝土耐久性研究

本文主要从四个方面研究了磁化水对混凝土耐久性的影响：孔结构、抗冻融性能、干缩和抗氯离子渗透性能.磁化水由自来水通过自主研制的MW-Ⅰ型磁水器而获得.试验中采用的磁化参数为磁场强度810mT,流速0.73m/s,磁场长度580mm.结果显示,磁化处理使混凝土总孔隙率下降20.8%,各龄期的孔级配改善.导致磁化水混凝土的干燥收缩有较大改善,90天相对收缩下降6%.冻融循环和抗氯离子渗透性能有较大的提高.     

Influence of drying methods on fractal geometric characteristics of mesoporous silica aerogels

Chemical modification/ambient drying method and freeze drying method were introduced to research the synthesis of mesoporous silica aerogels. By analyzing N2 gas adsorption/desorption isotherms, the fractal geometric characteristics of gels were focused. The overall surface fractal dimensions were determined by analyzing N2 gas adsorption branch and a Frenkel-Halsey-Hill (FHH) equation was empolyed to determine surface fractal dimension Df . It is found that, during ambient drying process, VTMCS/VWetgel ratio plays a crucial role in the changes of geometric feature, the key point is 50%, when the ratio is lower, and surface roughness increases with the ratio, when it exceeds 50%, the surface is almost unaffected by the modification. While freeze drying always tends to get larger Df , freeze drying process could cause a rough surface of the gels. Compared with traditional porosity and specific surface area analyses, fractal geometry may be expected to be favorable for mesoporous structural analyses of materials.     

不同体积掺量的TiO_2-SiO_2气凝胶对复合砂浆光催化性能的研究

具有锐钛矿相的Ti O_2-Si O_2气凝胶具有优异的光催化性能,试验将其与传统建筑材料复合,研究不同体积掺量的Ti O_2-Si O_2气凝胶对复合砂浆的密度、强度、导热性能及其光催化性能的影响规律。试验室自制的Ti O2-Si O2气凝胶取代骨料中的砂,取代率分别取0、40%、50%、60%、70%。结果表明:随着Ti O2-Si O_2气凝胶体积掺量的增加,砂浆的密度、抗压强度、抗折强度、导热系数均呈下降趋势,较未掺Ti O_2-Si O_2气凝胶的砂浆分别降低了56%、75%、59%、41%。而复合砂浆对甲基橙溶液的降解率随气凝胶体积掺量的增加,呈先升后降的趋势,当气凝胶体积掺量为60%时,降解效率达到最大,约80.24%。     

绿色生态混凝土技术的研究现状与发展

绿色生态混凝土技术是为了减轻地球环境负荷、与生态体系协调发展、创造舒适生活环境的混凝土材料.通过对绿色生态混凝土进行分类,论述了其研究现状和未来发展.绿色生态水泥混凝土是今后水泥混凝土行业发展的大趋势,这样才能使水泥混凝土行业走向可持续发展的道路.     

Microwave-assisted hydrothermal synthesis of carbon materials with tunable microstructure

A facile microwave-assisted hydrothermal route has been developed for a synthesis of versatile carbon materials. The monosaccharide fructose aqueous solution was adopted as the starting material, and the pH of the solution was adjusted to be in acidic (pH 4), neutral (pH 7) and basic (pH 10.5) conditions. The pH buffered fructose solutions were treated at different temperatures by a microwave-assisted hydrothermal technique. As-prepared carbon materials displayed pH and temperature dependent multi-morphologies (porous, spherical or core-shell), which were determined by transmission and scanning electron microscopic analyses (TEM and SEM). And the hypothesis of dehydration mechanism of hydrothermal synthesis was analyzed by ultraviolet extinction and Fourier transform infrared spectroscopy. It was found that as compared with normal hydrothermal synthesis, microwave assistance could efficiently increase the production yield and improve the spherical geometry of the carbon particles in neutral condition. By changing the pH of the system, acidic pH induces aggregation of the spheres, while basic pH produces more trends toward core-shell or sponge-like porous structure. The study opens a novel route to the production of polytropic carbon materials and suggests a potential niche market established from the green synthesis.     

磁化水对水泥拌合物性能的影响

本文主要研究了磁化水对水泥砂浆和净浆性能的影响。磁化水由自来水通过自主研制的MW-Ⅰ型磁水器而获得。试验中研究的磁化参数包括磁化器的磁场强度、水流通过磁场中心的流速、磁场有效长度、水流循环次数和养护时间。结果显示,采用磁化水拌制的水泥净浆流动度、胶砂试件强度和空白试样相比有很大的提高，当磁场强度达到810mT,水流速达到0.73m/s时,性能提高最为明显,水泥初凝时间可以提前30min～50min,砂浆抗压强度早期可提高20%～30%,28d强度增进率有所下降。