Suppression of Silver Diffusion in Borosilicate Glass‐Based Low‐Temperature Cofired Ceramics by Copper Oxide Addition

The silver diffusion behavior in the low‐temperature cofired ceramic (LTCC) comprising of borosilicate glass and alumina was investigated in this work. Transmission electron microscope (TEM) analysis revealed that silver ions diffused into LTCC materials through the glass phase. The addition of copper oxide in the LTCC materials can suppress the silver diffusion during the sintering process because of the enhanced crystallization of borosilicate glass, which leads to the quick increase in glass viscosity and retards the silver diffusion. Thermal dynamic analysis confirmed that the diffusion coefficient of silver in the copper‐oxide‐modified LTCC materials was largely reduced.     

Electrolysis of Soda-Lime Silicate Glass in Water

Thin glass bulbs made of commercial soda-lime glass were electrolyzed in aqueous solution. Ratios of mobilities of sodium and hydronium ions in the glass were calculated and compared to results of inter diffusion experiments with these ions. The results showed that a combination of electrolysis and ion exchange measurements can be used to test theories of the diffusion-controlled step in the reaction of water with glass, and that an interionic diffusion mechanism with complete ionization of the ions from SiO groups in the glass is the preferred mechanism.     

Sorption and diffusion of water in glass ribbon-reinforced composites

The processes of sorption and diffusion of water in anisotropic glass ribbon-reinforced composite films of controlled structural and physical characteristics were investigated in terms of the film properties, e.g., geometry, orientation, and volume fraction of the filler; molding characteristics of the composite film; and the adhesion between the glass ribbon and continuous cellulose acetate matrix. While the diffusion of water through unfilled cellulose acetate film was found to be a simple activated process with very little concentration dependence, the diffusion behavior of glass ribbon-reinforced cellulose acetate was found to be anomalous and concentration dependent.     

A free-volume interpretation of the influence of the glass transition on diffusion in amorphous polymers

A new version of the free-volume theory of diffusion is used to describe polymer–solvent diffusion both above and below the glass transition temperature. Expressions are derived for the temperature dependence of the mutual diffusion coefficient and for the effective activation energy in the limit of zero penetrant concentration. The theory also describes the effect of the glass transition on the diffusion process. Predictions of the theory are compared with available diffusivity data for amorphous polymer–solvent systems.     

Diffusion of Oxygen from Contracting Bubbles in Molten Glass

Some experimental measurements on the rate of contraction of oxygen bubbles in molten glass were compared with an equation for the diffusion- controlled contraction of a sphere. This comparison showed that the equation was valid until about 80% of the oxygen had diffused from the bubbles, so that the diffusion coefficient of the oxygen in the molten glass could be calculated from the experimental measurements. These values of the diffusion coefficient were higher than one would expect from the Stokes-Einstein equation for diffusion in liquids. Thus it was concluded that some short-circuiting mechanism such as diffusion in channels in the glass was operative. It also appeared that the oxygen diffused in the glass as atoms, rather than as molecules. From contraction measurements on glasses with different fining agents it was concluded that the mechanism of fining by such agents as antimony and arsenic oxides was not discharge of oxygen gas as had been generally supposed but was reduction of the concentration of oxygen in the glass, which caused the oxygen in the bubbles to diffuse into the glass more rapidly.     

Effect of Stress on Water Diffusion in Silica Glass

The diffusion of water in silica glass was measured as a function of applied uniaxial stress and hydrostatic pressure at selected temperatures. It was found that the diffusion coefficient of water increased exponentially with increasing tensile stress and decreased with increasing compressive stress and increasing hydrostatic pressure. The activation volume for water diffusion in silica glass was found to be ∼170 cm³/mol at 192°C and ∼72 cm³/mol at 350°C. The solubility of water in glass showed a trend opposite to the diffusion coefficient, namely, it decreased exponentially with increasing tensile stress and increased with increasing compressive stress and hydrostatic pressure. These stress (or pressure) dependences were attributed to the shift of the glass-water reaction equilibrium.     

Diffusion kinetics in the reaction of corundum refractories with a glass melt

Diffusion kinetics in contact of electromelted corundum refractories with the glass melt was investigated. The diffusion coefficients of Al³⁺ and their temperature dependence were determined. The basic tenets of diffusion kinetics in service of refractories in glass furnaces and feeder channels are examined.     

Microanalyses on the RuO2 Particle–Glass Matrix Interface in Thick-Film Resistors with Piezoresistive Effects

The piezoresistive mechanisms of composite thick films based on RuO₂ particles and both calcium-borosilicate and bismuth-borosilicate glass matrices were investigated by chemical and electrical microanalyses. The resistor based on bismuth-borosilicate glass showed higher sensitivity than that based on calcium-borosilicate glass. It was confirmed that the diffusion of ruthenium into glass affects the binding state of RuO₂ at the interface of the glass. Furthermore, an intermediate resistive layer is detected around the RuO₂ particle. These results suggest that the piezoresistive effect is related to a change in the electrical conductivity of the interfacial reaction layer caused by the diffusion of ruthenium into glass.     

溶胶-凝胶方法在玻璃表面制备ATO薄膜过程中Na+离子扩散的研究

利用金属醇盐以溶胶-凝胶方法制备了Sb掺杂SnO2(ATO)薄膜,研究了玻璃基板中Na+离子扩散对薄膜性能的影响及其机理,并进行了在玻璃表面预镀SiO2底膜以防止这种扩散的研究工作,发现预镀SiO2底膜后可以有效地阻止Na+离子的扩散从而改善了ATO薄膜的导电性能.     

Diffusion of seawater in unsaturated polyester resin and its glass fiber reinforced composites in the presence of titanium dioxide as UV absorber

Diffusion of seawater in unsaturated polyester resin (UPR) and its glass fiber reinforced composite in the presence of titanium dioxide has been studied by sorption method. Incorporation of glass and TiO₂ to UPR alters the seawater diffusion process from Fickian to non‐Fickian type. The dual mode sorption model is used to separate Fickian‐controlled and relaxation‐controlled diffusion in case of UPR‐T, UPR‐G, and UPR‐GT. The presence of TiO₂ seems to stabilize UPR and its glass reinforced samples but an increase in the rate of seawater diffusion is observed for these systems. The free volume determined from positron lifetime measurements support the diffusion data in these systems. Results further indicate that the contribution to diffusion in the later stages of sorption is due to the increased contribution from the interfaces. The plasticizing effect of TiO₂ is clearly seen even in the glass reinforced composite. DMA results show an increase in flexibility because of TiO₂ presence both in the neat as well as glass reinforced resin which is well supported by decrease in T_g value from DSC data. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2784–2794, 2006     

Concentration Dependence of the Diffusion Coefficient of Water in SiO2 Glass

The concentration dependence of water diffusion in SiO₂ glass was analyzed assuming that both molecular water and hydroxyl water can diffuse and that they are in equilibrium as interstitial and substitutional impurities. The equation obtained appears to be consistent with experimental observations of water diffusion in SiO₂ glass.     

Sodium Diffusion in the Nuclear Waste Glass GP 98/12

The diffusion of²² Na was measured in the nuclear waste borosilicate glass GP 98/12 in the temperature range of 350° to 450°C. The boundary condition of a thin initial tracer layer and serial sectioning were employed to measure the diffusion profiles. The activation enthalpy was found to be 1.08 eV. A parallel experiment with the base glass VG 98/12 not containing added (chemically simulated, inactive) waste showed that Na diffusion does not vary significantly when adding the waste.     

Mechanism of Preventing Crystallization in Low-Firing Glass/Ceramic Composite Substrates

The formation of a crystal phase in the glass matrix of low-firing glass/ceramic composite substrates limits the efficiency of the ceramic substrate when it is used in circuit boards. In the present study, adding approximately 30 vol % or more of alumina to a borosilicate-glass/ceramic composite system as a ceramic filler caused the diffusion of aluminum ions from the alumina filler into the glass matrix and prevented the formation of a cristobalite crystal phase. The diffusion distance between the aluminum ions was ∼30 μm when the system was fired at 900°C for 10 min. Raman spectroscopic analysis proved that some of the aluminum ions had diffused into the glass matrix during firing, working as a network former in the glass matrix. Raman spectra near 460 and 1100 cm⁻¹ indicate the change of network structure in the borosilicate glass. These phenomena indicate that crystallization of the borosilicate glass was prevented in the alumina-filled borosilicate system.     

浅议浮法玻璃气泡问题的分析与解决

在生产实践中,玻璃产品中的气泡问题一直是困扰玻璃生产厂家的一大难题。本文介绍了某玻璃企业玻璃产品出现气泡以后的观察、分析和解决过程,提出气泡的形成、变化、消失、再出现的过程,是气体在玻璃熔体中溶解和扩散的结果,了解各种气体在玻璃熔体中的特性和行为方式,有针对性地确定好玻璃熔化的温度曲线和燃料分配,这对减少玻璃中气泡是很重要的。     

Inward and Outward Diffusion of Modifying Ions and its Impact on the Properties of Glasses and Glass–Ceramics

In this paper, we review our recent findings about both the cationic inward and outward diffusion processes in glasses and glass–ceramics caused by redox reactions. We provide new insights into these findings by mapping the diffusion depth, the thermal reduction temperature, and time in a three dimensional diagram and by looking into the correlation among the glass composition, structure, topology, and the diffusion process in the polyvalent elements containing glasses. We illustrate the link between glassy dynamics (via the liquid fragility index m) and activation energy of diffusion. Furthermore, the inward diffusion approach is used to study percolation phenomena in glass–ceramics. Finally, we show that the diffusion approaches are potential tools for tailoring the surface performances of bulk glasses and glass fibers.     

Study of the mixed alkali effect in glasses and its relation to glass structure and alkali earth ion content

The mixed alkali effect in borosilicate glasses has been studied by diffusion and interpreted in terms of the glass structure parameters. Sodium and potassium diffusion couples were prepared and the interdiffusion zone studied. The glass structure influences the alkali ion diffusion; a mixed alkali effect is present. The smaller alkali ion, sodium, has a greater influence on the diffusion than the larger, potassium ion.

The influences of the alkali earth ions on the superimposed existing mixed alkali effect have been studied. The presence of magnesium, calcium and barium further decrease sodium and potassium diffusion coefficients by one or two orders of magnitude, in the interdiffusion zone. An explanation of these results lies in Dietzel's field strength theory of the mixed oxide effect in glasses.     

组成对铜离子扩散着色玻璃光谱性能的影响研究

红色玻璃以其鲜艳的色彩备受消费者的青睐。本文以氯化亚铜为主要原料,添加一定量的黏结剂和填充剂,在空气气氛中制备了铜离子扩散红色玻璃。研究发现组成中氯化亚铜、硫酸亚铁、氧化亚锡等对铜离子扩散着色有很大的影响。通过控制氯化亚铜、硫酸亚铁、氧化亚锡等的用量可以制备出应用广泛的红色玻璃。     

Kinetics of Dissolution and Diffusion of the Oxides of Iron in Sodium Disilicate Glass

The dissolution and diffusion of the three oxides of iron in sodium disilicate glass from 900° to 1100°C were controlled by diffusion in the molten glass. Concentration profiles were determined with an electron microprobe. Diffusion kinetics were applied on the basis of an ideal binary couple with concentration-independent inter-diffusivities. Concentration dependence of the inter-diffusivities was determined by the Boltzmann-Matano method, and the resulting interdiffusivities were interpreted in terms of a ternary diffusion model. The relation among the self-diffusion coefficients was

The activation energy for the interdiffusion process for all the iron oxide-sodium disilicate couples was 30 kcal.     

A multiscale model for quantifying helium diffusion in porous unsintered glass

Helium‐aided sintering of porous unsintered glass is a complex multiscale process, characterised by three different timescales, namely, that of helium diffusion, heat conduction, and radial shrinkage of the glass core. This work presents a multiscale model for quantifying heat and helium diffusion in a shrinking core system by decoupling the timescales based on their orders of magnitude. We obtain analytical solutions of our model, which allow us to quantify the spatio‐temporal profiles of temperature and helium concentration in the glass during the sintering process. Our results show that the introduction of helium increases the sintering rate of glass, and we conclude that pre‐sintering heating followed by helium‐aided sintering is better than simultaneous heating and helium diffusion. We also show that the pre‐sintering heating process for a standard glass sample should not be longer than an hour for the sake of heat economy, following which we may switch to the helium‐aided sintering process, where the sintering should occur under isothermal conditions for approximately 6 h. We perform dynamic simulations using glass porosity as a parameter, and find the sintering rate to be directly proportional to the initial porosity of the glass sample.