玻璃抗风压性能的研究

采用矩形大同玻璃试样，对风荷载作用下玻璃的变形及结构强度性能进行了研究，分析验算了破坏风荷载作用下玻璃强度的分布规律，在此基础上对玻璃设计的安全可靠性进行了探讨。     

熔制温度对铁硅酸盐玻璃体积电阻率的影响

在没有保护气氛情况下,对铁硅酸盐分别在不同熔制温度下进行熔制,并对玻璃进行电阻率测试,从而确定不同熔制温度对铁硅酸盐玻璃的体积电阻率的影响,进而分析不同熔制温度对电阻率影响的规律.为在无保护气氛下生产出电阻率达到1010数量级电阻玻璃提供熔制工艺技术依据.     

硅酸盐玻璃摩擦学研究进展与展望

硅酸盐玻璃在精密制造、高新技术等领域发挥着越来越重要的作用,然而硅酸盐玻璃材料的摩擦磨损性能却逐渐成为制约其应用与推广的关键问题之一,主要表现在硅酸盐玻璃的压痕损伤、划痕损伤及磨损损伤。分析了硅酸盐玻璃在制造及其服役过程中的关键摩擦磨损问题,阐述了硅酸盐玻璃摩擦学的研究内涵,对硅酸盐玻璃的压痕、划痕及磨损行为、机理和控制的问题进行了探讨,并结合硅酸盐玻璃摩擦学研究的现有进展及发展趋势,对硅酸盐玻璃摩擦学相关研究前景进行了展望。     

几种主要特种玻璃简介(连载一)

概述 特种玻璃包括特种浮法玻璃、硼硅酸盐玻璃、石英玻璃及碱土硅酸盐玻璃等具有高透性、高稳定性等特殊性质的玻璃,可用于航空、航天、电光源、太阳能、电子信息、高温高压容器、化学分析、卫生消毒、建筑装饰、建筑防火等场合。进入21世纪,特种玻璃的应用也越来越更为广泛。     

Al2O3对硼硅酸盐玻璃热膨胀和分相的影响

通过红外光谱分析了Al2O3取代SiO2后硼硅酸盐玻璃结构的变化,测试了玻璃的热膨胀系数和膨胀软化温度,通过扫描电子显微镜分析硼硅酸盐玻璃的分相,并结合X射线能谱分析了富硅相的组成.结果表明:硼硅酸盐玻璃中引入Al2O3后,随着Al2O3取代量的增加,玻璃结构中[BO3]增多,[BO4]减少;玻璃的热膨胀系数增大,转变温度和软化温度提高;硼硅酸盐玻璃中引入Al2O3后对玻璃的分相没有明显的改善作用.     

掺氟石英玻璃的研究

利用溶胶-凝胶法,以氟化铵(NH_4F)作掺氟源,使氟离子参与水解和聚合反应,经过热处理制成掺氟石英玻璃。在烧结时通入氟里昂(CCl_2F_2)进一步提高玻璃中氟重量含量直至2.50%。研究得出石英玻璃中氟含量与折射率、密度呈线性关系。氟有利于凝胶玻璃成块。用Raman和红外光谱研究掺氟石英玻璃结构,提出了氟进入玻璃网络的结构模型,并认为氟在玻璃中的存在状态为[SiO_3F]。     

硅酸盐激光玻璃

结合硅酸盐激光玻璃的最新进展和应用,系统、全面地介绍了硅酸盐激光玻璃的基本结构、性质、制备和研究方法等一系列问题,总结了近年来硅酸盐激光玻璃工业发展的理论和实验基础性研究,对硅酸盐激光玻璃可能的发展方向进行了展望.     

国内外特种玻璃研发与应用新动态

随着计算机信息技术、激光技术、原子能技术和红外技术等高新技术的应用和发展,玻璃产业特别是特种玻璃产业的发展十分迅速,已被广泛应用于光学、航空航天、核工业、生物医学等重要领域。本文对当今国际玻璃市场上走俏的石英玻璃、硼硅酸盐玻璃、特种浮法玻璃、透红外玻璃、耐辐照玻璃、特殊色散玻璃、透紫外玻璃等几种典型特种玻璃做了简介,同时介绍了我国特种玻璃的发展与现状的最新信息。     

石英玻璃结构研究的现状

玻璃态物质结构的研究在现代科学中占有一定的地位。探索石英玻璃内部结构,不仅可以丰富物质结构理论,而且能更好地指导石英玻璃生产实践。近半个世纪以来,人们提出了各种各样石英玻璃结构的假说。但是,由于涉及的问题比较复杂,至今尚未获得完全一致的     

结构弛豫对Al~(3+)/Yb~(3+)共掺石英玻璃结构和性能的影响

采用溶胶–凝胶法结合高温烧结工艺制备Al~(3+)/Yb~(3+)共掺石英玻璃,通过在玻璃转变温度(Tg)以下对玻璃进行等温退火,研究了退火时间对Al~(3+)/Yb~(3+)共掺杂石英玻璃密度、折射率和光谱性质的影响,并利用X射线衍射、Fourier转换红外(FTIR)、Raman光谱、核磁共振等结构分析手段探索其影响机理。结果表明:当退火温度为900℃时,随着退火时间增加,Al~(3+)/Yb~(3+)掺杂石英玻璃的折射率逐渐增大,紫外吸收边逐渐蓝移,Yb~(3+)离子的吸收和发射截面逐渐下降,退火200 h后Yb~(3+)离子出现2个荧光寿命;在Tg温度以下退火,玻璃的非晶态特征和Al的配位数不会发生明显变化;玻璃的假想温度及结构混乱度随退火时间增加逐渐下降。     

Hydration and reaction mechanisms on sodium silicate glass surfaces from molecular dynamics simulations with reactive force fields

Recent development of reactive force fields have enabled molecular dynamics simulations of interactions between silicate glasses and water at the atomistic scale. While multicomponent silicate glasses encompass a wide variety of compositions and properties, one common structural feature in these glasses is the combination of the network structure that is made up of silica tetrahedra linked through corner sharing interspersed with network modifiers like alkali and alkaline-earth ions that break up the Si–O–Si linkages by forming nonbridging oxygen. In reactions with water, ion exchange between alkali ions in the glass and proton or hydronium in the solution, as well as hydrolysis reaction of the Si–O–Si linkages and subsequent silanol formation, is observed and well documented. We have used a set of recently developed reactive force field to investigate the reactions between water and the surfaces of silica and sodium silicate glasses of different compositions for reactions up to 8 nanoseconds. Our results indicate sodium leaching into water and diffusion of water molecules up to 25 Å into the glass surface. We examined the structural and compositional changes inside the glass and around the diffused ions and use these to explain the rates of silanol formation at the surface. We also observed proton transport in the glass which has an indirect influence on the silanol formation rates. While the surface of the glass was rough to start with, it undergoes further modification into a hydrated gel-like structure in the glass for up to 5 Å in the higher alkali containing glasses. It was found that the leached sodium ions remain close to the interface and that fragments of silicate network from the surface is capable of dislodging from the bulk glass and enter the aqueous solution. These simulations thus provide insights into the formation and structure of an alteration layers commonly observed in multicomponent silicate glasses corroded in aqueous solutions.     

Dynamic and Static Fatigue of Silicate Glasses

Fatigue of silicate glasses was studied using both static and dynamic tests. Static fatigue data for acid-etched soda-lime silicate glass determined at 74°F in 50 and 100% rh can be represented by a single universal fatigue curve (UFC). The UFC for acid-etched glass does not lie on the UFC of Mould and Southwick, which was determined for abraded soda-lime silicate glass; the acid-etched glass was less susceptible to static fatigue. The susceptibility of acid-etched soda-lime silicate glass to static fatigue differed little from that of pristine E-glass and fused SiO₂ fibers. Dynamic fatigue data for soda-lime, E, borosilicate, and fused quartz glasses agreed well qualitatively and quantitatively with fundamental crack velocity data for these glasses; the dynamic fatigue theory of Charles was used in the comparison. The theoretical implications of these results are discussed.     

化学强化玻璃的发展现状及研究展望

化学强化玻璃因其表面压应力层使玻璃的机械强度提高,被广泛用于电子产品显示屏领域。本文对钠钙玻璃、铝硅玻璃、磷铝硅玻璃、锂铝硅玻璃等的化学强化进行了综述,对进一步通过优化骨干网络结构来提高玻璃本征强度获得更高机械强度的玻璃做出了可行性探索。总结了目前化学强化玻璃面临的问题及发展方向,为相关科学研究和工业生产提供参考。     

Dissolution Rates of Silicate Glasses in Water at pH 7

Dissolution rates of different glasses in buffered solutions of constant pH of 7 were measured by weight change, profilometry, and ion implantation with Rutherford backscattering. Rates with different techniques agreed within experimental error. Natural obsidian glass dissolved most slowly, at a rate comparable with those of quartz and crystalline aluminosilicate minerals. Commercial soda–lime glass containing alumina dissolved slowly, at about the same rate as vitreous silica; soda–lime silicate glasses both commercial and laboratory without alumina dissolved much more rapidly. Pyrex borosilicate glass dissolved at a rate intermediate between those of soda–lime silicate glasses with and without alumina; at room temperature Pyrex borosilicate glass dissolved about 100 times faster than a commercial soda–lime glass containing alumina. We suggest that surface structure is the main factor determining the relative dissolution rates of silicate glasses. Glasses with transformed surface layers caused by hydration dissolve most rapidly; phase separation and openness of the glass structure are also important factors.     

Transmission Electron Microscopy of Thin Glass Samples

Mechanical thinning and fracturing techniques for preparing thin glass samples for direct-transmission electron microscopy are discussed. A modification of the Doherty and Leombruno procedure for mechanically thinning ceramic materials is described. These techniques make possible more reliable electron microscope studies of fine-scale submicrostructure in glass systems. Electron microscope observations on fused silica, an alkali borosilicate glass, and some binary silicate glasses are reported and discussed in terms of present understanding of glass structure.     

Dielectric response and polarization mechanism of alkali silicate glasses in gigahertz to terahertz frequency range

Oxide glasses are dielectric materials with potential applications in high-frequency communications; hence, their dielectric properties in the gigahertz to terahertz frequency range should be investigated. In this study, the dielectric properties of silica glass and five single alkali silicate glasses were measured at 0.5–10 THz using terahertz time-domain spectroscopy and far-infrared spectroscopic ellipsometry. At 0.5–10 THz, the silica glass exhibited low dielectric dispersion with a low dielectric constant and loss. By contrast, the alkali silicate glasses exhibited high dielectric dispersion, and the dielectric constant and loss were higher than those of the silica glass. The shape of the dielectric dispersion profile depended on the alkali-metal ions; it was broader for lighter ions such as Li ions and sharper for heavier ions such as Cs ions. The peak dielectric loss shifted toward a lower frequency as the weight of the alkali-metal ions in the alkali-silicate glass increased. To understand the dielectric dispersion, the complex permittivity was calculated using molecular dynamics simulations. The theoretical results qualitatively agreed with the experimental data. Ion dynamics analysis revealed that alkali-metal ions vibrate and migrate under an applied electric field, which affects the dielectric constant and loss of alkali-silicate glasses at gigahertz to terahertz frequencies. To fabricate filter devices at low temperatures, alkali metals should be added to silicate glass; therefore, a minimum amount of light alkali metals should be used to minimize the dielectric loss of the glass materials while maintaining productivity.     

Mechanochemical Wear of Soda Lime Silica Glass in Humid Environments

The mechanochemical wear of multicomponent glasses was studied under controlled humidity conditions using a reciprocating ball‐on‐flat tribometer. For dry conditions, the surfaces were extensively damaged by scratching for all of the glasses, while for humid conditions the wear behavior varied with the glass composition suggesting a chemical effect on scratch behaviors of glass surfaces. The wear of soda lime silica (also called sodium calcium silicate) glass was suppressed with increasing humidity, while the borosilicate and barium boroaluminosilicate glasses showed an increase in wear volume with increasing humidity. The unique humidity dependence of the observed mechanochemical wear of soda lime silica glass supports the hypothesis that hydronium ion formation in the sodium‐leached sites of the soda lime glass enhances its wear resistance.     

Pattern Formation in Silicate Glass Corrosion Zones

Alteration zones of archeological glasses often show intriguing lamellar patterns in backscattered electron images. Here, we report results of static glass corrosion experiments with two different silicate glasses that revealed laminar porosity and subordinately chemical patterns inside silica-based corrosion zones that resemble those seen in naturally altered, ancient glasses. Aside from common laminar patterns, more complex patterns were observed in corrosion zones that developed along a fracture network. The formation of such patterns cannot be explained by any of the existing glass corrosion models. We suggest that silica-based corrosion zones form by a process that involves the congruent dissolution of the glass network, which is spatially and temporally coupled to the deposition of amorphous silica at an inwardly moving reaction interface. The patterns likely form in response to fluctuations of the pH and salinity in the interfacial solution, which govern the silica solubility, deposition, and dissolution rate, and thus, its microstructure and porosity, and, in turn, are controlled by the dissolution rate of the glass and the transport properties of the silica reaction layers. However, the exact feedback mechanism producing pH fluctuations in the interfacial solution has not yet been identified and is an open question for future research.     

Theoretical study of the thermal conductivity of silica glass–crystal composites

The heat dissipation of silicate glasses draws much attention for various applications, and the desire for glasses with high thermal conductivity remains an unsolved challenge. The structural origin of thermal conductivity in glass remains not fully understood. The present study aims to elucidate the impact of embedding highly thermally conductive crystalline α-quartz in a silica glass matrix. We consider both nano-thread (NT) (1D) and nano-plate (NP) (2D) structures and use molecular dynamics simulations to evaluate the role of its connectivity on thermal conductivity in the glass–crystal composite as a function of the volume fraction of the α-quartz region. The directional dependence of thermal conductivity was also investigated to obtain percolation threshold behavior along the cross-sectional directions, whereas the parallel circuit model of electricity can be used to account for the change of thermal conductivity along the longitudinal direction. Incorporation of α-quartz NTs or NPs into silica glass offers the opportunity to enhance its thermal conductivity.     

Investigation of Structure of Glasses by Their Infrared Reflection Spectra

Infrared reflection spectra of a number of glasses are presented. It is apparent that in some cases such a method may be a useful tool in determining the atomic arrangement in glasses, especially when combined with quantitative measurements of the refractive index and extinction coefficient. The dispersion curves of barium-containing silicate glasses show that the network of these glasses contains metals in at least two different types of coordination. One is obviously the silica tetrahedron and the other is probably a octahedrally coordinated barium. The latter is concluded by comparison with the reflection spectrum of benitoite. Reflection spectra of boric oxide glasses are presented. These indicate that pure boric oxide glass is not 100% triangularly coordinated and that the pure glass contains much more tetrahedral coordination than was previously concluded from X-ray-scattering data.