共查询到20条相似文献,搜索用时 97 毫秒
1.
2.
复合晶核剂(MoO3+CaF2)对铝硅酸盐玻璃析晶行为的影响作用研究 总被引:4,自引:0,他引:4
采用DTA,SEM,EDAX,SADP和XRD等测试方法研究了含复合晶核剂(MoO3+CaF2)的铝硅酸盐玻璃的分相与析晶行为。实验结果表明,含单一晶核剂CaF2或MoO3的玻璃仪产生表面析晶,而CaF2和MoO3共同引入时能诱导玻璃的体内核化,CaF2和MoO3均能降低基玻璃的析晶温度,整体析晶的机理是CaF2促进了玻璃的分相,MoO3富集子分相玻璃的富钙相中,热处理过程中优先析出了CaMoO4 相似文献
3.
介绍了制备具有梯度材料的生物微晶玻璃的热处理条件,讨论了影响材料物理性能的主要因素,应用XRD、SEM、EPMA等测试手段分析了材料的晶相分布。 相似文献
4.
5.
硫氮玻璃的析晶性能与结构分析 总被引:3,自引:0,他引:3
通过对二元(Ge-S)和三元(As-Ge-Se)系统硫系基玻璃和引入Si3N4的硫氮玻璃试样析晶性能的比较,对硫氮玻璃的析晶行为与其结构之间的关系进行了较深入的探讨。试验结果表明,随着Si3N4的引入,硫系玻璃的析晶温度得以提高或伴随析晶放热峰的消失。这表明氮原子的引入加强了硫系基玻璃微观结构的连缀度,使硫氮玻璃的析昌能力有所下降。此外还在经过析晶热处理的硫氮玻璃试样的XRD中发现两个新衍射峰,且 相似文献
6.
7.
8.
玻璃析晶动力学判据研究 总被引:21,自引:6,他引:21
本文综述了各种玻璃析动力学判据,在前人的研究基础上提出一种新的析晶动力学判据ky(T)=v.exp(-E/RT.△T/Tm)(其中△T=Tx-Tg),指出ky(T)值越大,玻璃稳定性越差;ky(T)值越小,玻璃稳定性越好。它将动力学因素与热力学因素结合起来,通过对Nd掺杂的氟锆酸盐玻璃,钛酸盐玻璃及Bi-Ca-Sr-Cu-O玻璃在不同升温速度,不同温度下的ky(T)计算,结果表明:ky(T)判据不 相似文献
9.
稀土掺杂硼铝硅酸盐玻璃形成和析晶性能 总被引:1,自引:0,他引:1
首先考察了稀土氧化物和氧化钡共掺入Al2O3-B2O3-SiO2玻璃的形成区范围、稀土氧化物掺入量对玻璃形成区的影响,然后利用差热分析手段分析了不同组分稀土氧化物对玻璃热稳定性的影响,最后采用XRD和TEM/EDS对在玻璃放热峰初始温度Tx附近热处理的玻璃样品进行了分析. 结果表明,当稀土掺入量逐渐增加时,玻璃形成区范围先扩大后缩小. 在Tx热处理温度附近,玻璃的失透主要由分相造成,稀土离子大量富集在富硼铝相中,热处理温度越高,玻璃的分相越明显;当继续在900℃下进行处理后,XRD谱图中出现了明显的析晶峰,通过分析比较认为主要析晶产物可能为类NdAl2.07(B4O10)O0.6结构的SmAl2.07(B4O10)O0.6晶体. 相似文献
10.
玻璃析晶难易的一种新判据 总被引:21,自引:8,他引:21
提出了用析晶动力学参数k=vexp(-E/RT)作为判别玻璃析品难易的新方法。指出这一方法较目前沿用的用析晶活化能E作判据的方法更能准确地反映玻璃析晶的难易程度。经过严格推导,得出修正Johnson-Mehl-Avrami公式ln(T_p~2/α)=ln(E/R)+E/RT_(p-lnv)。从此式可以方便、准确地获取析晶活化能E和频率因子v,从而得出k=voxp(-E/RT)。对高钛钡系统玻璃及氟化物玻璃的研究证实了k参数较R参数更能反映玻璃析晶的难易。 相似文献
11.
Luisa Barbieri Cristina Leonelli Tiziano Manfredini Cristina Siligardi Anna Bonamartini Corradi Piercarlo Mustarelli Corrado Tomasi 《Journal of the American Ceramic Society》1997,80(12):3077-3083
An aluminosilicate glass of composition 61SiO2 6Al2 O3 10MgO6ZnO·12Li2 O·5TiO2 (mol%) has been prepared by a melting process and investigated as far as crystallization is concerned. Glass-ceramic is easily obtained because glass shows a high tendency to crystallize starting from 700°C. The crystalline phases evolve with temperature, showing the aluminosilicates to be the main phase up to 1050°C, followed by metasilicates and silicates, some of which have lower melting points. The titanates of Mg and Zn develop from the phase-separated glass, soon after T g , and grow to form nucleation centers for the other crystalline phases. The evolution from phase-separated glass to glass-ceramic has been followed by many thermal, diffractometric, spectroscopic, and microscopic techniques. 相似文献
12.
13.
14.
Results of a study of sintering and crystallization of lithium aluminosilicate-based glass ceramic prepared by casting aqueous high-density slips into porous molds are reported. Optimum conditions for the formation of structure and phase composition of the glass ceramic and the development of required properties are established. 相似文献
15.
John M. Jewell Marie S. Spess Renee L. Ortolano James E. Shelby 《Journal of the American Ceramic Society》1991,74(1):92-97
The effects of isochronal heat treatments on the properties of a lithium aluminosilicate glass have been measured. Heat treatment of the base glass at temperatures between 700° and 1100°C initially results in phase separation of the glass, followed by the formation of β-quartz solid solution ( ss ) at about 850°C. The β-quartz( ss ) converts to β-spodumene in the temperature range between 950°C and 1000°C. The dependence of the properties of the material on the heat-treatment temperature is controlled by phase separation below 850°C, by the rapid crystallization of β-quartz( ss ) between 850°C and 900°C, and by the lack of change in morphology with heat treatment above 900°C. The effects of heat treatment on the properties of this material are explained on the basis of the changes in the composition and morphology of the residual amorphous and crystalline phases. 相似文献
16.
Revealing and understanding the microscopic origins of the macroscopic properties of aluminosilicate glasses is important for the design of new glasses with optimized properties. In this work, we study the composition‐structure‐property relationships in 20 MgO/CaO sodium aluminosilicate glasses upon Al2O3‐for‐SiO2 and MgO‐for‐CaO substitutions. We find that some properties (density, molar volume, Young's modulus, and shear modulus) are linear through the investigated range of Al2O3 compositions, while others (refractive index, coefficient of thermal expansion, Vickers hardness, isokom temperatures, and liquid fragility index) exhibit a change in the slope around the composition with [Al2O3] = [Na2O], which is especially pronounced for the glasses containing MgO. We discuss these phenomena based on structural information obtained by NMR spectroscopy and topological considerations. 相似文献
17.
18.
作为重要的透明微晶玻璃体系,含镁锌的铝硅酸盐玻璃展现了优异的力学、光学特性。大量研究关注该体系的核化和晶体生长过程,但锌镁替换对铝硅酸盐玻璃玻璃转变和晶化行为影响的物理机理尚不明晰。本研究以xZnO·(11-x)MgO·22Al2O3·67SiO2(x%=0%,2.2%,5.5%,8.8%,11.0%,摩尔分数)玻璃为研究对象,探究锌镁替换对铝硅酸盐玻璃的玻璃转变和晶化行为的调控规律。结果表明:随着锌逐步替换镁,玻璃转变温度慢慢下降,这是由于Zn2+较弱的场强和多一个电子层的屏蔽作用,玻璃网络骨架整体键合强度降低;析出晶相从单一的莫来石相转变为莫来石与锌铝尖晶石的混合相,这是由于Zn2+具有促进铝硅酸玻璃分相的作用;析晶温度降低,这主要是由于析晶温度附近黏温曲线变得更陡峭和析晶活化能降低。 相似文献
19.
无碱铝硅酸盐玻璃是一种应用范围较广的特种玻璃。介绍了该种玻璃在高压液位计、卤素灯及无碱基片方面的应用,提出了应用中存在的问题及发展趋势。 相似文献
20.
熔盐中少量的Na+并不会对玻璃的离子交换效果产生明显影响,但当熔盐中Na+浓度不断增大时,化学增强钠铝硅酸盐玻璃的性能开始受到影响。本文采用一步法离子交换工艺研究了熔盐中Na+浓度对不同厚度化学增强钠铝硅酸盐玻璃表面压应力、应力层深度和弯曲强度等性能的影响。研究表明:熔盐中Na+浓度不断增大时,化学增强钠铝硅酸盐玻璃的表面压应力、弯曲强度下降;弯曲强度下降最多可达175 MPa,此时玻璃的表面压应力下降了57.4 MPa;熔盐中Na+浓度变化未对化学增强钠铝硅酸盐玻璃的应力层深度和可见光透过率产生明显影响。 相似文献