Aqueous Corrosion of Soda-Silica and Soda-Lime-Silica Glass

Corrosion of a 20Na2O-10CaO-70SiO₂ (mol%) glass by water was investigated using ir reflection spectroscopy, solution analysis, electron microprobe, and Auger electron spectroscopy. Corrosion proceeds at a much slower rate in the ternary glass than in a 20Na2O-80SiO2 glass. Within the Na-depleted layer of the ternary glass, a Ca-enriched zone develops—1500 A from the surface. The role of CaO in both the early and later stages of corrosion is discussed.     

A New Low-Brittleness Glass in the Soda-Lime-Silica Glass Family

In the soda-lime-silica glass family, the effect of each constituent of the composition on the brittleness was first investigated. Vickers indentation was employed to estimate the brittleness (ratio of harness ( H ) to fracture toughness ( K _c)) by measuring the C / a ratios (where C and a are the characteristic crack and indentation diagonal lengths, respectively). It was observed that a higher silica content and a lower lime content helped to lower the brittleness. Substitution of potash and magnesia for soda and calcia, respectively, was effective in lowering the brittleness. From these results, a higher molar volume was found to be a key factor for reducing the brittleness. A new low-brittleness glass was then developed with a brittleness as low as 5.1 µm^-1/2 as compared with the brittleness of 7.1 µm^-1/2 for commercial soda-lime-silica glass. The crack initiation load ( P *), measured by the Vickers indentation method, for this new low-brittleness glass was almost 10 times as high as P * of commercial soda-lime-silica glass. The new glass shows lower hardness and higher fracture toughness than the commercial soda-lime-silica glass.     

Reactive Vaporization of Soda-Lime-Silica Glass Melts

Water-vapor-assisted transport of glass constituents from a soda-lime-silica melt was studied, using atomic spectroscopy for analysis of vapor condensates and microprobe analysis to determine diffusion profiles. The data presented indicate that the vaporization process is controlled by a surface membrane which has a composition different from the bulk composition. The influence of this effect on glass homogeneity is discussed.     

N31型磷酸盐激光钕玻璃的耐水性

通过测试N31型掺钕磷酸盐激光玻璃在水浴中质量损失随时间的变化情况,讨论了该玻璃在水溶液介质中的化学稳定性和微观侵蚀机理.结果表明:N31型玻璃化学稳定性良好,在水溶液介质中各离子都有自身的溶解规律;经过一段线性溶解过程后,各离子的溶解速率明显下降,这是由于在钕玻璃局部表面生成了保护膜.     

Mechanical Behavior of a Borosilicate Glass Under Aqueous Corrosion

In France, fission products are being vitrified for a possible final geological disposal. Under disposal conditions, corrosion of the glass by groundwater as well as stress corrosion because of stresses occurring at surface flaws cannot be excluded. Within this framework, the mechanical behavior of the French simulated nuclear waste glass SON68 was studied by Vickers indentation and fracture experiments in air and in a corrosive solution. The glass was corroded at 90°C in a solution enriched with Si, B, and Na. The results showed that the glass corrosion enhances the cracks propagation relative to experiments in air. The indentation fracture toughness ( K _{I C} ) obtained using a four-point bending test showed that the K _{I C} of the glass decreased with increasing corrosion time.     

Subcritical Growth of Indentation Median Cracks in Soda-Lime-Silica Glass

The influence of load and dwell time on the subcritical growth of indentation cracks was investigated. The behavior of soda-lime-silica glass in both active and inert environments was considered. Vickers indentations were obtained.using loads ranging from 1.96 to 39.2 N and the dwell time.at maximum load was varied between 5 s and 30 min. Indented samples were broken and the fracture surfaces.observed using optical microscopy. Anomalous crack shapes were obtained in air and water for long dwell times, particularly at higher indentation loads. The cracks were markedly circular in shape and substantially deeper than conventional median/radial indentation cracks, evidencing a time-dependent growth. Comparison of the measured crack depth with a theoretical analysis demonstrated that the appearance of the "circular" cracks was related to the subcritical growth of median cracks.     

Strength Degradation of Soda-Lime-Silica Glass During Dynamic Loading

The strength degradation of soda-lime-silica glass during dynamic loading was studied by using a fracture-mechanics approach. The theoretical and experimental results indicate that subcritical flaw growth during loading causes the strength degradation.     

Development of Porous Antireflective Films on Soda-Lime-Silica Glass

Glass compositions were surveyed to identify candidates that could be heat-treated to produce an interconnected phase-separated structure needed for porous antireflective films and which matched the viscosity-temperature characteristics needed for the float glass process. A glass composition of 10% Na₂O,10% CaO, and 80% SiO₂ meets these criteria. Microstructural development and film-formation kinetics were characterized to permit definition of appropriate heat-treatment and selective dissolution processes. Broadband antireflective characteristics were developed on treated glass surfaces.     

Methanol Vapor Adsorption on Silica and Soda-Lime-Silica Glass

Methanol vapor adsorption isotherms on vitreous silica and soda-lime-silica glasses were measured by gas chromatography in the low-pressure region of the physical adsorption isotherms after the adsorbents had been degassed in a dry atmosphere at successively higher temperatures. The isosteric heats of adsorption indicate that after strong degassing treatments each methanol molecule is adsorbed by the formation of a single hydrogen bond with the surface, but after low-temperature degassing more than one hydrogen bond is formed for each adsorbed molecule.     

Effect of Deuterium Oxide on Crack Growth in Soda-Lime-Silica Glass

Crack growth in acidic and basic deuterium oxide solutions was studied. An isotopic effect was observed in basic deuterium oxide solutions but not in acidic deuterium oxide solutions. The results suggest that the rate-limiting step for crack growth difsers for basic and acidic environments.     

Detection of Reaction Products Between Water and Soda-Lime-Silica Glass

A simulated extract approach was used to ascertain the identities of the products of reaction between a soda-lime-silica glass and water. The reaction between the glass and water was studied at 90° C. with reaction time periods up to 4 hours. The products of this reaction were found to be sodium metasilicate, calcium meta-silicate, and metasilicic acid.     

Temperature Dependence of the High-Frequency Viscoelastic Behavior of a Soda-Lime-Silica Glass

The high-frequency viscoelastic behavior of a soda-lime-silica glass has been investigated using the Brillouin scattering technique. The temperature dependence of instantaneous elastic constants and very short-time relaxation mechanisms have been measured in a temperature range between 100° and 1000°C. Variations in the elastic constants in the transition region are significant, and have to be taken into account for numerical computations of tempering and annealing of glasses. A complex thermorheological behavior is observed for very fast relaxation mechanisms in the transition range, whereas intermediate and slow relaxation mechanisms exhibit a simple thermorheological behavior. The viscoelastic behavior of this glass can be adequately represented by assuming a different thermorheological behavior in the alpha- and β-relaxation regimes.     

Anelasticity of Glass: II, Internal Friction and Sodium Ion Diffusion in Tank Plate Glass, A Typical Soda-Lime-Silica Glass

The internal-friction peak observed near room temperature in tank plate glass at a period of the order of seconds and previously attributed to sodium ion diffusion is further discussed. The temperature of maximum internal friction is shown to vary with the frequency of vibration with an activation energy of about 16 kg.-cal. Per mole for air-chilled glass fibers. Likewise, the activation energy for the electrical resistivity of the chilled glass is about 16 kg.-cal. Although the activation energy for sodium ion diffusion and alkali durability is about 21 kg.-cal., it too can be properly interpreted to confirm that the internal friction peak is caused by sodium ion diffusion. The internal friction peak is much broader than can be accounted for by a single relaxation mechanism. However, a dispersion of relaxation mechanisms is consistent with the accepted theory of randomness in the silica network.