溶胶凝胶法制备SiO2工艺

以正硅酸乙酯（TEOS）为主要原料，乙醇为溶剂，盐酸或氨水等为催化剂可制得硅酸凝胶．探讨了溶胶凝胶反应的机理及催化剂、水、溶剂及反应温度等对胶凝时间、凝胶的黏度、结构等的影响．采用先酸性后碱性的两步Sol-Gel法可大大缩短胶凝时间．     

溶胶凝胶法聚醋酸乙烯酯/二氧化硅有机无机杂化材料的制备及表征

通过溶胶-凝胶方法制备了均匀透明的PVAc-SiO     

溶胶凝胶法聚醋酸乙烯酯／二氧化硅有机无机杂化材料的制备及表征

通过溶胶－凝胶方法制备了均匀透明的PVAc-SiO2有机无机杂化材料,用ET－IR、SEM及溶剂抽提对材料进行了结构表征,用DSC及密度测试对材料进行了性能表征。     

溶胶—凝胶法SiO2陶瓷膜的制备与应用

本文采用溶胶－凝胶法以正硅酸乙酯为原料，乙醇为溶剂，盐酸为催化剂，Ｎ，Ｎ－二甲基甲酰胺为成膜助剂，在多孔陶瓷管载体上制得了ＳｉＯ２膜，并探讨了其制备及乙要不，     

溶胶—凝胶法制备硅灰石超细粉体

以正硅酸乙酯(TEOS)、硝酸钙[Ca(NO3)2·4H2O]为原料,采用溶胶 凝胶法制备了CaO SiO2干凝胶粉末。在适当的条件下制备粒径为0.2～1.0μm的硅灰石粉体。研究发现热处理温度、时间对粉体粒度有较大影响。采用DTA、XRD等研究了CaO SiO2凝胶粉末在热处理过程中的物理、化学变化及晶相转变,并通过TEM观察了干凝胶粉末热处理产物的形貌。     

溶胶—凝胶法制备Nd_2O_3—SiO_2二元体系干凝胶的研究

本文讨论了以正硅酸乙酯及硝酸钕为原料,加入少量二甲基甲酰胺、乙二醇作为络合剂,采用溶胶—凝胶法制备Nd_2O3—SiO_2二元系统干凝胶的过程,分析了络合剂在干燥过程中所起的作用,同时对干凝胶的烧结过程及改变溶液组成对凝胶的影响进行了初步的探讨。     

AlOOH溶胶的制备及其结构与性能表征

以AlCl3.6H2O和氨水为原料、硝酸为解胶剂,采用非均相沉淀法制备了AlOOH溶胶,并通过喷雾干燥法制备了AlOOH溶胶的凝胶粉体。利用TEM、激光粒度分析和ζ-电位测量等考察表面活性剂对AlOOH溶胶粒径分布以及稳定性的影响,采用SEM、BET、XRD等分析煅烧后AlOOH溶胶干燥物的显微形貌、比表面积、孔径分布以及晶化机理。结果表明,添加PEG400可以控制AlOOH溶胶胶粒的尺寸和粒径分布范围;溶胶经喷雾干燥处理后得到的凝胶粉体流动性好,颗粒呈圆环状或圆钵状,具有较高的比表面积,且经过1200℃煅烧后其比表面积仍可达185 m^2/g。     

钛硅分子筛TS-1的合成和表征及其催化性能

采用导向剂法在水热体系中制得Ts-1分子筛，合成过程中大大减少了TPAOH的用量，解决了钛硅分子筛TS-1合成成本昂贵的问题。并采用XRD、FT—IR、UV—Vis和SEM对所合成的分子筛进行了表征，还考察了所合成的分子筛催化苯酚羟基化的反应性能。结果表明：采用导向剂法在适宜条件下可以合成出高结晶度的TS-1分子筛，产品为正交晶系，钛以四配位的形式存在于分子筛中；合成的TS-1分子筛具有良好的选择催化氧化性能。     

以TEOS为硅源的聚硅硫酸铁制备与除藻性能

采用正硅酸乙酯（TEOS）代替传统的硅酸钠制备活性硅酸,将活性硅酸与聚合硫酸铁反应合成聚硅硫酸铁混凝剂,并研究了相关机理。由于正硅酸乙酯水解很缓慢,容易控制,可以得到重现性好的产物,有利于进行除藻性能的研究。通过正交实验等研究获得了聚硅硫酸铁的优化合成条件,即铁硅摩尔比为1．0,反应温度为50℃和反应时间为60min。论文还研究了优化条件下合成的聚硅硫酸铁混凝剂除藻性能,得到除藻优化条件,即原水的pH值为11．0、预氧化剂的投加量为0．70mg／L,聚硅硫酸铁的投加量为24．1mg／L。     

TiO2水溶胶对棉织物的拒水整理探讨

采用溶胶-凝胶技术制备的TiO2水溶胶,对棉织物进行后整理,对不同浓度的TiO2水溶胶整理棉织物后的耐水压值和淋水级数进行了测定,结果显示具有一定的拒水性能,并对织物表面拍摄了扫描电镜照片．     

Preparation and characterization of silica gel powders

ＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＳＩＬＩＣＡＧＥＬＰＯＷＤＥＲＳＬｉＺｈｏｎｇｊｕｎＺｈａｏＱｉｎｓｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＮｏｎｆｅｒｒｏｕｓＭｅｔａｌｕｒｇｙ,ＣｅｎｔｒａｌＳｏｕｔｈＵｎｉｖｅｒｓｉｔｙ...     

Preparation and characterization of polyimide/silica hybrid films

Polyimide (PI) thatserves as a typical kind of en-gineering polymer material has been used widely in aer-ial, nuclear and microelectronic industries because ofits outstanding characteristics, such as excellent ther-mal stability, relatively high tensile strength and modu-lus and, especially, preeminentelectrical properties in-cluding low dielectric constant[1]. But the pure poly-imide also has many disadvantages, such as high wetta-bility, thermal expansivity and poor corona-resistance.Moreove…     

Experiment on the silica sol imbibition of low-permeability rock mass: With silica sol particle sizes and rock permeability considered

It’s a universal engineering problem to seal micro-cracks of low-permeability argillaceous rock mass by grouting in the fields of civil engineering and mining. This paper achieved the grouting sealing of low- permeability artificial rocks with the permeability of 0.1–40 mD by adopting silica sol imbibition grouting. The variation characteristics of particle size, viscosity, and contact angle of silica sol during solidification and the pore size distribution of low-permeability artificial rocks were measured, and spontaneous imbibition tests of the artificial rocks were carried out. Finally, combined with the imbibition theory, percolation theory, and fracture medium grouting principle, the silica sol imbibition mechanism of low-permeability rocks and soil was discussed. The results show that: (1) Silica sol can be injected into artificial rocks with the minimum permeability of 0.1 mD through spontaneous imbibition; (2) The particle size increase of silica sol leads to decreased wettability, affinity, and injectability in grouting materials; and (3) In the range of 0.1–40 mD, the grout absorption first increases and then decreases with increased permeability. The number of large pores and fractures in the rock mass is related to injectability, and the number of small and medium pores is related to the internal driving force of imbibition. This study provides a theoretical basis for silica sol grouting sealing of low-permeability argillaceous rocks and is, therefore, an important reference for application.     

用于压电悬臂梁的PZT厚膜的溶胶-凝胶制备及表征

研究了一种用于制备硅基压电悬臂梁的PZT厚膜溶胶-凝胶工艺.该工艺通过采用交替旋涂法,将PZT溶胶与PZT纳米粉混合形成浆料,再和澄清PZT溶胶交替涂覆在Au/Cr/SiO2/Si的硅基悬臂梁结构上,当达到所需的厚度后再进行热处理.实验证明,热处理温度在650℃,处理时间15 min时,XRD结构表征显示PZT厚膜获得钙钛矿相结构,SEM中厚膜断面清晰,表面紧密、均匀、平整.铁电性能测试表明矫顽场为50kV/cm,饱和极化强度为54μC/cm2,剩余极化强度为30μC/cm2.同时,硅基悬臂梁结构采用典型的半导体光刻工艺,利用BHF/HCl溶液成功地刻蚀了PZT厚膜,并运用微机械加工技术刻蚀出硅悬臂梁结构.     

改良单质硅溶解法制备大粒径硅溶胶的研究

在一定的温度和压力条件下,采用单质硅溶解法,用正交试验法研究了反应温度、反应压力、反应时间、氢氧化钠及硅粉用量等对硅溶胶收率及粒径的影响。实验结果表明,硅溶胶制备实验的最佳工艺条件如下：压力为0.5 MPa,在200 mL去离子水中加入15 g硅粉和0.4 g氢氧化钠,并控温度为160℃反应9 h,在此条件下制得的硅溶胶平均粒径为174.4 nm,收率为80.15%。平行实验结果表明,该最佳工艺条件具有良好的重现性。     

低品位硅藻土的硅溶胶包覆和焙烧改性

硅溶胶与硅藻土两者本身含有羟基,两者结合易形成氢键或发生脱水反应产生化学作用力,使硅溶胶易附着于硅藻土上对其进行包覆从而对其微孔进行封闭,而焙烧能使硅藻土中的有机物等其他杂质分解而起到扩容的效果。本实验利用溶胶凝胶法制备硅溶胶对硅藻土的开孔结构进行封闭处理,对其焙烧提高其保温性能同时减低其吸水率。通过扫描电镜、差热分析、导热系数与吸水率等测试手段对改性后的硅藻土进行了测试分析。讨论了硅溶胶和硅藻土之间的作用机理,探讨了硅溶胶用量与焙烧温度对硅藻土性能的影响。研究表明,当硅溶胶占硅藻土质量的40%,焙烧温度为500℃,其质量吸水率从131%降低至为71%,导热系数由0.171 6 W/(m·K)降为0.089 5 W/(m·K)。     

Facile and controlled synthesis of silica sol nanospheres through a modified sol-gel process

An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through the optimized synthesis in which the mixture of tetraethyl orthosilicate （TEOS） and ethanol was followed by the addition of water and ammonium hydroxide （NH3） separately, and the size of silica sol spheres was strictly controlled in the range of 25-119 nm with a narrow size distribution by fine adjustment of several reaction parameters. Results showed that in the presence of low concentration of TEOS, spheres size rose first and reached maximum when H2O concentration was up to 66 g/L. However, the diameter of silica sol spheres decreased above 66 g/L of H2O concentration. Furthermore, it was also found that the size and size distribution of silica sol nanospheres were affected by NH3 concentration. As NH3 concentration increased from 15 to 35 g/L, the diameter declined from 83 to 64 nm. Nevertheless, higher NH3 concentration would result in relatively broad size distribution, and gelation occurred when NH3 concentration reached 44 g/L. In addition, the effect of the different feed rates ofNH3 on the size growth of silica sol nanospheres was also discussed.     

基于溶胶凝胶法的TiO_2溶胶的制备

用N-N二甲基乙酰胺（DMAC）作溶剂,钛酸丁酯作前驱物,冰乙酸为稳定剂,通过溶胶凝胶法制得了二氧化钛（TiO2）溶胶,并且对加水方式、加水量、溶剂量、pH值、温度等影响因素进行了考察。结果表明,当采用分散加水方式,温度在25℃～35℃以下,DMAC与钛酸丁酯的体积比为3.5：1,V（H2O）/V（Ti（OC4H9）4）为2～3,pH值为2～4时所得TiO2溶胶稳定,透明性好,可用作聚合物与纳米二氧化钛复合膜的研制的添加剂。     

Preparation and characterization of natural rubber/silica nanocomposites using rule of similarity in latex

Rule of similarity and latex compounding techniques were combined for the first time to prepare natural rubber/nanosilica (NR/SiO₂) nanocomposite with core-shell nanosilica-poly (methyl methacrylate) (SiO₂-PMMA) particles and PMMA-modified natural rubber matrix (NR-PMMA). The microstructure of SiO₂ and nanocomposites with different SiO₂ contents was characterized by fourier transform infrared spectroscopy (FTIR); the morphology of nanocomposites was investigated with scanning electron microscopy (SEM); the tensile strength was characterized by tensile testing machine and the thermal stability of composites was studied by thermal gravimetric analysis. Results showed that PMMA chains have successfully grafted onto the surface of SiO₂, and the core-shell SiO₂-PMMA nanoparticles and NR-PMMA latex have been perfectly incorporated. SiO₂-PMMA nanoparticles are evenly distributed over the NR matrix with an average size in the range of 60–100 nm at the low content (SiO₂≤ 3 wt%), while aggregations are apparently observed when 5 wt% SiO₂ is loaded. In addition, NR/SiO₂ composities possess a considerable improvement in ageing resistance compared with the pure NR. The tensile strength of composite increases from 6.99 to 12.72 MPa, reaching the highest value at a 0.5 wt% SiO₂ loading, and then the figure decreases gradually because of the aggregation of SiO₂ nanoparticles. It is anticipated that the reported process is to provide a simple and economic way for preparing NR composites.