若干硫系玻璃黏度变化速率的结构起源探索

用熔融淬冷法制备Ge₃₃As₁₂Se₅₅、Ge₂₂As₂₀Se₅₈、Ge₁₀As₄₀Se₅₀、As₄₀Se₆₀、Se硫系玻璃,采用流变仪测试样品黏弹状态的黏度,计算各样品黏度的Vogel-Fulcher-Tammann 方程和黏度变化速率(即料性)。结合拉曼光谱,根据玻璃微观结构对料性的影响规律进行系统分析。发现随着Ge_xAs_ySe_100-x-y硫系玻璃中Ge、As含量的增加,玻璃黏度随温度的变化速率先降低再升高,料性先变长后变短。在平均配位数=2~2.6时,随着平均配位数的增大,组成玻璃的原子之间的平均键能和网络结构稳定性逐渐变大,黏度变化速率降低,料性变长;在=2.6~2.78时,随着网络结构中As-As/Ge-Ge缺陷键的出现,玻璃网络结构的稳定性降低,玻璃黏度的变化速率加快,料性变短。     

高温黏度测试在浮法玻璃生产组分调整中的应用

利用ORTON高温旋转黏度计测试生产线玻璃组分在调整前、后的黏度-温度曲线,通过黏度-温度曲线分析玻璃内在热学性质的变化情况,根据不同温度段的黏度变化情况制订出合理的调整熔化工艺参数方案,可缩短生产过程中组分调整时间,减少无效作业时间,提高产品质量。     

多孔羟基磷灰石陶瓷的制备与性能研究

将羟基磷灰石粉末与过氧化氢、聚乙烯醇等物质混合成型、干燥、烧结,制得孔径理想、互通性能良好的多孔羟基磷灰石陶瓷.通过对制备方法、组分、工艺条件等不同因素的研究,探讨这些因素对羟基磷灰石性能的影响.由压汞仪测得制品的气孔率随粘结剂含量的增大而降低.用SEM对其表面微观形貌进行观察.     

Effect of Al203/SiO2 Ratio on the Viscosity and Workability of High-alumina Soda-lime-silicate Glasses

通过采用旋转式高温黏度计和线膨胀系数测定仪,对不同 Al2O3/SiO2质量比的高铝型钠钙硅玻璃的黏度、玻璃化转变点（Tg）以及膨胀软化点（Tf）进行相应地测定研究。基于 Vogel–Fulcher–Tamman （VFT）公式理论,玻璃的黏度与温度存在一定的函数关系,由此得到了玻璃在锡槽成形温度段的黏度,通过 Arrhenius 公式理论推算其黏质活化能,由此探讨 Al2O3掺量对玻璃熔体料性的影响。通过 Ramman 光谱对玻璃结构进行研究,[SiO4]四面体基团 Qn（n = 1,2,3,4）的变化反应了玻璃结构的改变。结果表明：在高铝型钠钙硅玻璃中用 Al2O3替代 SiO2,可使玻璃熔体黏度增大且料性变短,伴随着玻璃结构中 Q3/Q2比例降低,同时可推算得到锡槽成型过程中各工艺段的温度。     

Creep Viscosity and Stress Relaxation of Gel-Derived Silicon Oxycarbide Glasses

The temperature dependence of the viscosity and stress-relaxation kinetics of sol–gel-derived SiOC glasses that contain up to 14 at.% carbon have been characterized in the temperature range of 1000°–1400°C. The viscosity, as determined from relaxation experiments, is in good agreement with the creep viscosity and is typically two orders of magnitude higher than the viscosity of vitreous silica. However, materials suffer from partial crystallization at >1150°C, and the precipitation of β-SiC nanocrystals induces a flow-hardening behavior and results in a dynamic increase in viscosity, especially at >1200°C and for glasses with a high carbon content.     

Bending Creep Test to Measure the Viscosity of Porous Materials during Sintering

A bending creep test is proposed for measuring the change in viscosity of a porous material during densification. Equations, based on simple beam deflection theory, were derived to obtain the viscosity from a series of loading experiments using rectangular samples of different densities. By measuring the deflection in the center of the specimen between the spans, the viscosity of a porous material during densification can be measured. Experiments with porous Y₂O₃-stabilized ZrO₂ beams were used to illustrate the bending creep test. Consistent with theory the viscosity increased from 50 to 400 GPa·s as the sample densified from 87% to 98% density. The rapid increase in viscosity was considered to be a result of both densification and grain growth.     

Measurement of Viscosity of Densifying Glass-Based Systems by Isothermal Cyclic Loading Dilatometry

This study describes the isothermal cyclic loading dilatometry (ICLD) technique to measure the viscosity of glass-based materials. We demonstrate its merit relative to constant-load techniques in minimizing the stress history effects (changes in shrinkage anisotropy and sample microstructure) that arise due to the application of an external load. A constant-load test overestimates the viscosity by an order of magnitude compared with a cyclic load test. To obtain accurate viscosity data, maximum loading rates and longer unloading periods are desirable as they reduce effects of shrinkage anisotropy on viscosity values. Representative data for a low-temperature cofired ceramic (LTCC) material are reported. Nonparametric statistical tests revealed insignificant differences between the viscosity data sets at 5% significance level and thus indicate good reproducibility of the testing methodology.     

Shear and Densification of Glass Powder Compacts

Sinter-forging types of experiments were carried out on powder compacts of glass. The shear and densification strains were measured simultaneously during the forging process. This information was analyzed to obtain the shear viscosity of the glass and the intrinsic sintering pressure, both as a function of density. The viscosity of the porous glass changed nonlinearly with density and was empirically fitted to an exponential function. The sintering pressure was found to increase with density; it was 100 kPa at ρ= 0.55 and 250 kPa at ρ= 0.90. In this range the sintering pressure could be adequately described in terms of a simple geometrical model. However, when the density approached 95%, the sintering pressure appeared to assume an uncertain value. The measurements were also used to calculate the viscous bulk modulus of the porous glass; these estimates agreed well with theoretical prediction.     

Viscosity of glass‐forming systems

As one of the most important properties of glass‐forming liquids, viscosity has drawn significant attention in both glass manufacturing and fundamental research. We review the recent scientific progress in viscosity of glass‐forming systems, including both the liquid and glassy states. After the Vogel‐Fulcher‐Tammann (VFT) equation was introduced, many more efforts have been made to develop more accurate models to describe the temperature dependence of viscosity. In addition to the VFT equation, we also discuss three other viscosity models, viz., the Adam‐Gibbs, Avramov‐Milchev, and Mauro‐Yue‐Ellison‐Gupta‐Allan models. We compare the four viscosity models in terms of their theoretical underpinnings and ability to fit measured viscosity curves. The concept of fragility and the universality of the high‐temperature viscosity limit are also discussed. Temperature‐dependent constraint theory is introduced in detail as a powerful tool for predicting the composition dependence of viscosity. Some examples of the application of this approach to predict the glass transition temperature and fragility of various glass systems are shown. Topological constraint theory is not only of scientific interest, but also has important industrial applicability. We also discuss the thermal history dependence of viscosity in the glassy state. Some phenomenological models are briefly reviewed, while the main focus is given to the modified Mauro‐Allan‐Potuzak model, which can accurately predict the nonequilibrium viscosity as a function of temperature, thermal history, and composition. The correlation of viscosity with elasticity is described in terms of the shoving model. Some theoretical implications of the various viscosity models are discussed, including the concepts of the Kauzmann paradox and the ideal glass transition. Some of the evidence against the existence of these phenomena are discussed. We also review the link between glass relaxation and viscosity, that is, emphasizing that the viscosity equations presented in this review can also be used to model different types of relaxation effects based on the Maxwell relation.     

About the Realistic Porosity of Porous Glasses

Nitrogen adsorption, mercury intrusion, scanning electron microscopy and small-angle X-ray scattering have been used to determine the texture properties of a selected mesoporous glass. The glass has been prepared by a combined acid and alkaline leaching treatment of a phase separated sodium-borosilicate initial glass. Residues of silica gel, remaining in the pores of the investigated glass after the treatment with alkaline solution, lead to differences in the results of the standard characterization techniques nitrogen adsorption and mercury intrusion.In order to explain these differences, small-angle scattering experiments in combination with scanning electron microscopy have been performed.Here, a well-defined range order L 60 nm has been selected and a 50% porosity results. The behaviour of the second derivative of the small-angle scattering correlation function has been checked by the use of the linear simulation model.     

废玻璃烧结法制备多孔玻璃

本文采用回收的废玻璃在高于玻璃化转变温度下短时间烧结制备出具有一定孔隙度和强度的过滤用多孔玻璃.废玻璃破碎成细颗粒后过筛,并在32 MPa的压力下模压成型,压坯在640℃到670℃的温度区间内烧结.实验结果表明,试样在670℃烧结30 min可以获得合适的抗弯强度(12.84 MPa)和开孔率(29.4％),此时的多孔玻璃具有明显的烧结颈,平均孔径为10 μm左右,平均氮气通量和水通量分别为13600 m3 m-2h-1bar-1和693.4 m3 m-2h-1 bar-1.     

Effects of Water Content on the Properties of Sodium Aluminosilicate Glasses

Sodium aluminosilicate glasses of the general formula 25Na₂O. x Al₂O₃.(75 – x )SiO₂ were prepared with a range of hydroxyl contents. Both the glass transformation and isokom temperatures decrease as the hydroxyl content increases. The magnitude of the decrease in each property is a function of the alumina content of the glass, with the largest effects occurring for the glass containing 25 mol% Al₂O₃. The magnitude of the effect of water as a function of alumina content reflects the decrease in the concentration of nonbridging oxygens in the glass with increasing Al₂O₃ content, since the effect of the terminal hydroxyl species on the connectivity of the glass is enhanced by the elimination of nonbridging oxygens. The results indicate that the large effect of water content on the properties of these glasses must be considered when discussing the role of alumina in glasses.     

影响多孔玻璃孔结构的因素

研究表明,利用填充法制备的多孔玻璃的孔参数(气孔率、孔径分布)可进行设计与控制,多孔玻璃的气孔率和孔径分布主要取决于成孔剂的体积比及其颗粒分布,前者与后者之间的偏差取决于生坯制备及烧结过程.     

ZrO2对高硼硅玻璃高温粘度和表面张力的影响

高硼硅玻璃由于熔化温度高,对耐火材料侵蚀严重,ZrO2溶解到玻璃中后使其高温粘度和表面张力发生变化,是产生玻璃缺陷的重要原因之一。通过在母体玻璃中引入少量ZrO2,采用旋转粘度法测试玻璃的高温粘度,采用静滴法测试玻璃的高温表面张力。结果表明,随着含量的增加,ZrO2对玻璃在1530℃以上的粘度影响不大,但可使1530℃以下的粘度有较大提高。玻璃的高温表面张力随着ZrO2含量的增加单调递增,随着温度的升高而降低。     

Effect of Water Concentration on the Properties of Commercial Soda-Lime-Silica Glasses

The effect of water concentration on the properties of three commercial soda-lime-silica glasses has been measured. Water (H₂O) concentration varied from 50 to 550 ppm-wt. Properties measured include glass transformation temperature, transformation range viscosity, thermal expansion coefficient, electrical conductivity, and refractive index. The viscosity, T _g, and electrical conductivity decreased with increasing water content, while the thermal expansion coefficient and refractive index were unaffected by changes in water concentration.     

Tansformation Range Viscosity Measurements Using a Thermomechanical Analyzer

A commercial thermomechanical analyzer has been adapted to determine the transformation range viscosities of very small samples using a beam-bending configuration. Three viscosity standards—NBS-710, NBS-711, and NBS-717—have been used to determine the accuracy of this technique over a wide range of temperatures. The method yielded excellent results that were independent of sample size and heating rate. The largest deviation from National Bureau of Standards data was 3.8°C at 10¹⁰ Pa's for one sample of NBS-711; the average deviation at 10¹⁰ Pa's was approximately 2°C for all samples studied. In all cases, the activation energy for viscous flow was in excellent agreement with that calculated from National Bureau of Standards data.     

Al2O3/SiO2比对高铝型钠钙硅玻璃黏度及料性的影响（英文）

通过采用旋转式高温黏度计和线膨胀系数测定仪,对不同Al2O3/SiO2质量比的高铝型钠钙硅玻璃的黏度、玻璃化转变点(Tg)以及膨胀软化点(Tf)进行相应地测定研究。基于Vogel–Fulcher–Tamman(VFT)公式理论,玻璃的黏度与温度存在一定的函数关系,由此得到了玻璃在锡槽成形温度段的黏度,通过Arrhenius公式理论推算其黏质活化能,由此探讨Al2O3掺量对玻璃熔体料性的影响。通过Ramman光谱对玻璃结构进行研究,[SiO4]四面体基团Qn(n=1,2,3,4)的变化反应了玻璃结构的改变。结果表明:在高铝型钠钙硅玻璃中用Al2O3替代SiO2,可使玻璃熔体黏度增大且料性变短,伴随着玻璃结构中Q3/Q2比例降低,同时可推算得到锡槽成型过程中各工艺段的温度。     

Properties of Nitrogen-Containing Yttria—Alumina—Silica Melts and Glasses

The viscosity and solubility of nitrogen in Y₂O₃–Al₂O₃–SiO₂ melts have been systematically examined. The effects of nitrogen content on viscosity for Y-Al-Si-O-N melts and on Vickers hardness of oxynitride glasses also have been examined. Although the viscosity of Y₂O₃–Al₂O₃–SiO₂ melts was decreased, the solubility of nitrogen into the melts was increased with increased Y₂O₃ content. These results indicated that the yttrium ion behaved as a network modifier. Therefore, the structural units for viscous flow became small, and the amount of nonbridging oxygen increased in the melts when the Y₂O₃ content increased. The viscosity of Y-Al-Si-O-N melts and Vickers hardness of oxynitride glasses remarkably increased with increased nitrogen content. These results suggested that the substitution of nitrogen for oxygen in the melts may have led to a high average coordination of nonmetal atoms and that the increased cross-linking produced a more rigid glass network.     

含铅玻璃及其无铅化的研究

介绍了铅对人体的危害,综述了一些为限制铅的使用及排放而制定的相关法规,详细介绍了铅玻璃在现阶段中的一些主要用途和目前人们对这些玻璃的无铅化方面的工作。指出电子产品无铅化的迫切性。     

Order Distance Estimation in Porous Glasses via Transformed Correlation Function of Small-Angle Scattering

A mesoporous two-phase system, consisting of colloidal silica in the cavities of the main silica frame work of a macroporous glass, was investigated by use of Small-Angle X-ray scattering. The transformed correlation function _T(r) was determined for this material for distances r<40 nm. The application of the intrinsic properties of _T(r) yields estimations for two fundamental order distances L ₁=11 nm and L ₂=120 nm of the~porous glass possessing a clear geometric interpretation: L ₁, a short-order-range, is the mean chord length of the mesopores plus the mean chord length in the secondary particles. L ₂, a long-order-range, is an estimation of the mean diameter of a macropore plus the mean free distance in the silica framework which separates two nearly parallel segments of two adjacent macropores.