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硝酸锶对水热合成硬硅钙石球形团聚体的影响 总被引:4,自引:1,他引:3
硬硅钙石是一种用途广泛的保温材料,本工作以硝酸锶作为矿化剂,研究了在动态水热合成硬硅钙合成中,硝酸锶对硬硅钙石球形团聚体的影响。研究表明:在合成时添加硝酸锶,可以使水化硅酸钙(C-S-H)凝胶的ξ电位的绝对值减小,从而C-S-H胶团的凝聚长大,C-S-H凝胶粒度的增大是硬硅钙石球形团聚体增大的基础,Sr^2 进入到硬硅钙石晶体内引起其晶胞常数a和c的增大,促进硬硅钙石的纤维状晶体以及球形团聚体的长大,从而有利于得到轻质硬硅钙石材料。 相似文献
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硬硅钙石水热合成的形成历程及硝酸锶对它的影响 总被引:7,自引:2,他引:5
利用XRD,SEM,TEM等方法对动态水热法合成硬硅钙石的形成历程进行了研究,由C-S-H凝胶不能在高于200℃温度下稳定存在,使硬硅钙石在180℃和220℃时的形成历程不同,配料中加入硝酸锶,提高料浆的离子强度,产生原盐效应,降低了C-S-H凝胶的生成速率,延缓了硬硅钙石的形成,硬硅钙石合成过程中的料浆中固体粒子的ζ电位是不断变化的,加入硝酸锶,可以降低料浆固体粒子ζ电位的绝对值,有利于硬硅钙石纤维状晶体以及团聚体的长大。 相似文献
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《耐火材料》2017,(5)
为提高硬硅钙石制品的耐压强度,首先将预处理后的石英粉、消化后的Ca O、添加剂、去离子水(按水、固质量比为30量取)置于磁力搅拌高压釜中,在220℃分别保温0、1、3和6 h后得到相应产物,探究硬硅钙石的合成;然后,在制得的硬硅钙石粉体中分别加入0、5%、10%、15%和20%(w)的预处理陶瓷短纤维,经压滤成型和烘干后,于1 000℃保温2 h烧成,研究陶瓷纤维加入量对硬硅钙石试样烧成前后耐压强度的影响。结果表明:在硬硅钙石的合成过程中,首先生成C-S-H凝胶,然后C-S-H凝胶转化形成托贝莫来石,最终托贝莫来石完全反应生成了硬硅钙石;陶瓷纤维的引入提高了硬硅钙石试样烧成前后的耐压强度,当加入15%(w)陶瓷纤维时,耐压强度最大;1 000℃烧成前后试样中的物相分别是硬硅钙石相和硅酸钙相,烧成后试样的耐压强度比生坯试样的大。 相似文献
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采用动态水热法,以硅酸钠钙为原料合成硬硅钙石晶须,通过搅拌使晶须形成高孔隙率的球形颗粒. 考察了温度、时间和原料CaO/SiO2摩尔比等反应条件对硬硅钙石晶须及其球形颗粒孔隙率的影响. 结果表明,将CaO和SiO2按摩尔比0.90~1.15溶于Na2O浓度为20 g/L的NaOH溶液中,控制液固比为30 mL/g,以300 r/min的转速在220℃下水热反应7 h以上,可制备出直径约200 nm、长径比大于20的硬硅钙石晶须,晶须相互缠绕形成的球形颗粒孔隙率最高可达93%. 相似文献
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用稻壳灰水热合成硬硅钙石的研究 总被引:7,自引:0,他引:7
研究了用稻壳灰作硅质材料水热合成硬硅钙石。结果表明,在合理选择钙硅比、水固比、搅拌时间,反应时间、反应温度等水热合成条件的情况下,稻壳灰中的SiO2能够与Ca(OH)2反应生成硬硅钙石晶体,并且这种纤维状的晶体还能相互交织成二次球形粒子。 相似文献
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为探究不同硅质原料对水热合成水化硅酸钙物相的影响,研究了温度和硅钙比对产物的影响。采用X射线衍射(XRD)分析了水化硅酸钙物相,并探究了不同硅质原料与Ca(OH)2的反应效率。结果表明,不同硅质原料与Ca(OH)2的反应效率由高到低依次为硅藻土、石英、珍珠岩;在硅藻土-石灰体系中,硅藻土中非晶态二氧化硅的Si—O更易被破坏,具有不稳定性,致使硅藻土反应效率更高。在石英-石灰体系中,随着钙硅比的提高,空气中的CO2参与反应,生成碳硅钙石与片柱钙石,且托贝莫来石与硬硅钙石会逐渐消失,通过合理调控硅钙比和水热温度可有效地控制反应产物,这对于不同硅质原料的选择、水热合成水化硅酸钙中产物的控制及水热合成水化硅酸钙应用领域具有重大意义。 相似文献
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ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l/3为氧气,2/3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中:A一混… 相似文献
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P. P. Budnikoff 《Journal of the American Ceramic Society》1924,7(11):817-820
The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO3 and determination of CaO by KMnO4 titration, the SO3 by Andrews method of titration of BaCrO4 has been found to give very reliable results with the least consumption of time. 相似文献
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A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases. 相似文献
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A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
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ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES 总被引:5,自引:0,他引:5
Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log10 viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log10 viscosity as a function of soda content are smooth up to 50% Na2O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO2, 2Na2O) due to Molecular Substitution of CaO, MgO and Al2O3 for Na2O The effect is clearly brought out by plotting (from the results of English) the change of log10η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature Ta. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log10η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A12O3) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al2O3) per 100°. At the aggregation temperature the change of log10η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al2O3. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log10η due to substitution of an oxide for Na2O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na2O-CaO-SiO2. Change of Viscosity of Glass (4SiO2, 2Na2O) due to of Substitution of B2O3 for SiO2 The change of log10η (from the results of English) is plotted as a function of temperature, and also the change of log10η per per cent B2O3. The curves are more complex than for the substitution for Na2O. 相似文献
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面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。 相似文献