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1.
刘继翔  罗世永 《玻璃》1996,23(4):6-9,5
本文用振动光谱分析了Na2O-Al2O3-B2O3-SiO2系统溶胶中的化学反应和用浸渍法制备的凝胶涂层结构。结果表明:部分硼、铝在溶胶陈化初期就与Si(OC2H5)4的水解或缩聚产物反应形成线性聚合物,宜于浸涂。热处理时涂层中继续形成Si-O-Si、Si-O-Al和Si-O-B键;基本结构单元为[SiO4]、[BO4]、[BO3]和[AlO4]。  相似文献   

2.
对Si-C-O-N系统进行了平衡状态下的相稳定性计算,绘制了在1473K和1573K下的Si3N4、SiC、Si2N2O和SiO2相稳定性与N2分压和O2分压的关系图以及N2分压和SiO分区的关系图,Si3N4/Si2N2O/SiC、SiO2/Si2N2O/SiC两个三固相平衡点与N2分压、O2分压和SiO分压以及温度的函数关系日。并以此确定C纤维-SiC纤维转变和C纤维上涂层SiC过程中,为获得稳定SiC相的气体分压。  相似文献   

3.
耐高温低膨胀玻璃的研制   总被引:1,自引:0,他引:1  
本文采用溶胶-凝胶法制备了SiO2-B2O3系凝胶玻璃,研究了硼酸,酸度,温度对凝胶温度的影响,用红外光谱分析了不同组分及不同热处理制度的SiO2-B2O3二元系凝胶玻璃,在该系统中,硼皆以Si-O-B状态存在于玻璃网络中,采用熔融凝胶玻璃的方法制备了SiO2-B2O3-Al2O3玻璃,B2O3含量大于10wt%,具有软化点大于1000℃膨胀系数在15×10^-7/℃左右的物理性能,可用于氪灯钨杆  相似文献   

4.
根据Si-C-O-N系统的相稳定性计算,绘制了于平衡状态下相稳定性与N_2分压和O_2分压以及相稳定性与N_2分压和SiO分压的关系图,发展了以气态SiO与碳纤维反应将碳纤维转变为SiC纤维,以及气态SiO与CO反应于碳纤维上形成SiC涂层的新方法。本文介绍这两种方法的工艺原理和主要实验结果。  相似文献   

5.
凌志达 《硅酸盐学报》1994,22(3):288-294
根据Si-C-O-N系统的相稳定性计算,绘制了于平衡状态下相稳定性与N2分压和O2分压以及相稳定性与N2分压和SiO分压的关系图,发展了以气态SiO与碳纤维反应将碳纤维转变为SiC纤维,以及气态SiO与CO反应于碳纤维上形成SiC涂层的新方法。本文介绍这两种方法的工艺原理和主要实验结果。  相似文献   

6.
刘素兰  李香平 《硅酸盐通报》1996,15(6):11-15,10
采用粉末烧结方法制备MgO-B2O3-SiO2三元系不同组成的样品,用X-射线衍射、岩相和化学分析方法结合研究了1100℃40≤MgO%〈60组成范围内的相关系,结果表明可用3MgO.B2O3-2MgO.SiO2-2MgO.B2O3,2MgO.B2O3-2MgO.SiO2-MgO.SiO2,2MgO.B2O3-MgO.SiO2-SiO2三个三角形表示各平衡相的相关系。应用重心规则计算平衡相量与组成  相似文献   

7.
采用粉末烧结方法制备MgO-B2O3-SiO2三元系中不同组成的样品。用X-射线衍射、岩相和化学分析方法相结合研究了1100℃40≤MgO%<60组成范围内的相关系,结果表明可用3MgO·B2O3-2MgO·SiO2-2MgO·B2O3,2MgO·B2O3-2MgO·SiO2-MgO·SiO2,2MgO·B2O3-MgO·SiO2-SiO2三个三角形表示各平衡相的相关系。应用重心规则计算平衡相量与组成的关系,其结果可用回归方程表示,并可作为控制富硼渣的理想组成的根据。  相似文献   

8.
溶胶—凝胶法制备SiO2膜的研究   总被引:11,自引:0,他引:11  
研究了正硅酸乙酯和硅溶胶水解聚合过程中溶胶聚合物分子的生长过程。用TEOS和硅溶胶作原料。用溶胶-凝胶法制备了有载体和无体体的SiO2膜,由不同原料引起的聚合物分子的不同生长模式将引起无载体SiO2膜孔径的较大差异,用TEOS制得的无载体SiO2膜无1.7nm以上的孔,而用硅溶胶制得的SiO2膜平均孔径为7.5nm且孔径分布狭窄。用TEOS作原料可在载体α-Al2O3上制得无大孔缺陷厚约0.8μm  相似文献   

9.
溶胶—凝胶法制备TiO2—SiO2玻璃的研究   总被引:1,自引:0,他引:1  
王华林  余锡宾 《玻璃》1999,26(2):1-4
讨论了溶胶-凝胶法制备组分范围为xTiO2(100-x)SiO2(x=5,10,20,30mol%)的掺杂CO2。研究了各种掺杂条件对掺杂玻璃物化性能及结构的影响,TiO2-SiO2玻璃结构均一,反射率较高,透光性良好,能广泛应用于光学元件,如光学纤维等。  相似文献   

10.
本文以原硅酸四乙酯Si(OC2H5)4,五水硝酸锆Zr(NO3)4·5H2O为基础原料,以无水乙醇(C2H5OH)为溶剂,以盐酸水溶液为催化剂,利用Si(OC2H5)4的水解和硝酸锆的溶解制备SiO2和7ZrO2·93SiO2纤维凝胶,并将其在不同温度下进行热处理,得到SiO2和7ZrO2·93SiO2玻璃纤维。测定了SiO2和7ZrO2·93SiO2溶液的粘度变化,并将热处理后的凝胶纤维与玻璃纤  相似文献   

11.
液相法制备碳—碳复合材料Si—W涂层表面氧化层的结构   总被引:8,自引:0,他引:8  
研究了一种液相法及其它方法制备的碳-碳复合材料多层防氧化涂层,并用XRD,SEM,Raman光谱和EMPA研究了液相法制备的Si-W涂层表面氧化后的结构。研究结果表明;氧化后涂层表面生成石英玻璃,且由于W的高价氧化物进入玻璃的分子网络结构,使其能长时间保持稳定而不析晶。  相似文献   

12.
Devitrification resistance is one of the most important properties of silica fibers. The devitrification behavior of silica fibers made by the acid leaching method, the sol-gel method, and the high-purity silica fusing method, and the effects of small amounts of Al2O3 and B2O3, were studied by using X-ray diffraction. The results indicated that the devitrification tendency of silica fibers made by the high-purity silica fusing method is apparently greater than that of the fibers made by the other two methods. A small amount of B2O3 has the effect of retarding devitrification, while Al2O3 promotes devitrification of the fibers. The combined effect of Al2O3 and B2O3 is to strongly enhance the devitrification of silica fibers. The results are discussed in the context of structural analysis.  相似文献   

13.
张焱  黄三喜  祖群  黄松林 《硅酸盐通报》2017,36(11):3936-3943
采用高温熔融法制备了SiO2-Al2O3-MgO系统的S级高强玻璃纤维,研究了不同玻璃组分对玻璃耐酸性能的影响,利用扫描电镜(SEM)、红外光谱(IR)和核磁共振(NMR)等手段分析了酸侵蚀前后纤维的表面形貌和微观结构,进而分析了S级高强玻璃纤维在酸腐蚀环境下的破坏机理.结果表明:S高强玻璃的结构主要由硅氧四面体[SiO4]和铝氧四面体[AlO4]等构成,随着酸蚀的进行,玻璃网络结构被破坏,Si-O-Si断裂形成Si-OH键并形成凝胶附着在纤维表面;而铝氧多面体中Al-O键断裂,Al3+逐渐从玻璃结构中被置换出来,导致玻璃网络中Al3+浓度大大降低;高强系列玻璃的耐酸性能与玻璃表面的化学组成以及玻璃内部的微观结构关系密切.致密的玻璃网络结构有利于抑制H+对玻璃结构破坏,抑制阳离子与H+的置换作用;此外引入离子场强高的Ti4+,由于"积聚"作用而使玻璃结构致密,提高玻璃纤维的耐酸性.  相似文献   

14.
Optical fibers are often made using a flame hydrolysis deposition process, in which silica and doped silica particles from a soot-laden flame are deposited on a target rod. The porous preforms thus formed are subsequently sintered into glass blanks and then drawn into optical fiber. We review here various tools that have been developed for better understanding of different processes involved in the making of optical fibers using the outside vapor deposition technique. Fundamental understanding of the different unit operations involved in the optical fiber manufacturing is critical for process optimization and improved product attributes.  相似文献   

15.
In our study, mesoporous carbon fibers were prepared by using electrospinning and physical activation. In order to develop mesoporous structure, silica was used as a physical activation agent due to meso-size of particle. The diameter of activated carbon fibers increased and surface became rougher after physical activation. Textural properties of carbon fibers were evaluated by using surface pore structure analysis apparatus. The specific surface area increased 12 times and total pore volume increased about 57 times through physical activation using silica. The development of mesoporous structure was confirmed by pore size distribution and fraction of micropore volume. From the DFT pore size distribution, it is sure that broad meso-sized porous carbon fibers were obtained from physical activation in our experiment. The fact that fractions of micropore volume are too low showing less than 2% by the results of total pore volume and HK pore volume concedes that silica activated CFs are pretty mesoporous. Eventually activated carbon fibers having broad meso-sized pores were obtained successfully.  相似文献   

16.
Electroblowing and sol–gel reaction were combined to prepare mesoporous silica fibers. Poly(methyl methacrylate) (PMMA), a simple commercial polymer with weak hydrogen bonding to silica, was demonstrated to be valuable in improving the electrospinnability and as a porogenic agent. Compared with that in electrospinning, the jet stream in electroblowing was more stable and the resultant fibers were more uniform. The electroblown fibers were characterized by infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption and desorption isotherms. The phase separation behavior and mechanism for the formation of the amorphous mesoporous structure were discussed. Although there was no covalent bonding between PMMA and silica, macrophase separation was completely prevented in the electroblown fibers and the pore size in the calcined silica fibers ranged from 10 to 20 nm. However, the previously reported electrospun silica fibers, in which surfactants or polymers with strong hydrogen or covalent bonding to silanol groups were used as structure directing agents, had average pore sizes below 10 nm. The present study offers a facile method for the preparation of highly mesoporous silica fibers with large mesopores.  相似文献   

17.
The, Theological properties of suspensions of relatively small amounts of titanate fibers in polystyrene solution have been measured by means of a Weissenberg rheogoniometer. The titanate fibers employed have diameters smaller than 0.5 micron and aspect ratios higher than 40. It has been found that the rheological properties of the suspensions are markedly time dependent; the steady-flow shearing stress increases with increasing time when the rate of shear is changed abruptly from an initial high value to a considerably lower final value. This behavior can be attributed to the re-formation of a structure formed by the dispersed fibers and broken at higher shear rates. The dynamic storage modulus G′ also depends strongly upon the re-formation of the structure. Although the structure reformation process under shear appears too complicated to be analyzed satisfactorily, an attempt has been made to generalize the experimental data with a simple equation.  相似文献   

18.
煤与垃圾衍生燃料的混烧技术   总被引:2,自引:1,他引:2  
简要分析了我国的城市垃圾处理现状 ,介绍了垃圾衍生燃料的种类、制作方法及国内外研究进展。鉴于我国城市垃圾热值低、灰分高的特点 ,建议将垃圾制成垃圾衍生燃料后掺混到现运行的燃煤锅炉中 ,以实现资源化利用。统计了该方法在国外的运行情况 ,并对我国采取该方法的可行性进行了分析。论证结果表明 ,该方法投资省、污染低 ,对我国的环境卫生建设和经济建设具有重要意义  相似文献   

19.
使用乙二醇作为稀释剂将硅溶胶稀释,得到不同浓度的硅溶胶溶液,用作涂覆商用碳纤维的原料。碳纤维表面改性后涂覆硅溶胶溶液,取出后在Ar气氛中于1 600 ℃保温30 min,硅溶胶涂层与碳纤维发生碳热还原反应形成SiC覆盖层。对制得的产物进行形貌和结构表征,并根据热力学数据对SiC包覆层的生长动力学和高温扩散机制进行研究。计算结果表明,反应过程为扩散控制。SiC/C纤维比碳纤维有更优异的耐高温氧化性能,为低成本制备新型陶瓷纤维提供可借鉴的思路和热力学依据。  相似文献   

20.
水泥基复合材料邻近集料表面最近间距分布的解析解   总被引:2,自引:0,他引:2  
陈惠苏  孙伟  STROEVEN P  SLUYS L J 《硅酸盐学报》2005,33(7):859-863,870
依据Torquato的最邻近表面函数公式,推导出了水泥基复合材料邻近集料表面最近间距分布的解析解。采用计算机模拟方法生成了一个模型,选取邻近集料表面最近间距概率密度分布曲线和累计概率分布曲线两个参数,对比模拟结果与理论结果之间的差别。通过比较发现,该理论解析解与模拟试验结果能够很好地吻合。利用该解析解,研究了在常用集料体积分数下,符合Fuller分布的砂浆和混凝土中邻近集料表面最近间距分布及邻近集料表面最近间距平均值随集料体积分数和集料细度的变化关系。  相似文献   

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