Surface -OH Profile from Reaction of a Heavy-Metal Fluoride Glass with Atmospheric Water

The surface -OH profile in a 15BaF₂-28.3ZnF₂-28.3YbF₂-28.3ThF₄ (mol%) glass resulting from reaction with atmospheric water for 22.5 h at 344°C was determined by monitoring the 2.9-pm absorption band as material was removed from the surface by polishing. The -OH penetrated -10 pm into the surface. The-OH concentration profile agreed with that predicted from a diffusional analysis, allowing determination of the surface -OH concentration; this corresponded to replacement of one of seven F⁻ ions with OH⁻.     

Stress in Leached Phase-Separated Glass

When a phase-separated glass is leached, stresses develop because of release of thermal stresses, creation of surface area, ion exchange, and hydration. Analyses are presented for the thermal stresses, including the portion that develops on cooling from the heat-treatment temperature to the setting temperature of the less viscous phase. During leaching, the interfacial energy of the residual phase increases, so that phase tends to contract. A more important effect is the contraction caused by removal of alkali and B₂O₃ from the residual phase during leaching. The extent of removal of B₂O₂ decreases with heat-treatment time, t_H , because the scale of the microstructure increases as t^1/3_H. The change in residual B₂O₂ content with t_H is shown to be consistent with diffusion-controlled ion exchange. The dependence of stress on t_H in partially leached glasses, measured by Drexhage and Gupta, results principally from the change in extent of ion exchange; the reduction in surface area with increasing t_H also has a significant effect on the stresses.     

Partially Reduced Cuprous Oxide Nanoparticles Formed in Porous Glass Reaction Fields

This paper describes the formation of cuprous oxide (Cu₂O) particles ∼10 nm in diameter and their reduction by hydrogen gas in porous glasses. Nanoparticles of Cu₂O coated with metallic copper are expected to show high third-order optical nonlinear susceptibilities (χ⁽³⁾). The porous glass is a medium in which nanoparticles can be partially reduced without forming agglomerations. Images obtained using transmission electron microscopy showed that particles with the desired core-shell structure were actually formed, even though some particles were not reduced uniformly from the surface. The χ⁽³⁾/α (α: absorbance) values in relevant conditions (10⁻¹³ esu·cm) were similar to that of copper because of the formation of a byproduct of copper nanoparticles on reduction.     

Surface Characterization of Zirconia After Reaction with Water

Ultrafine ZrO₂, Y₂O₃, and TZP (ZrO₂+-3 mol% Y₂O₃) powders were reacted with water under various conditions; hydration of their particle surfaces was investigated by measuring electrophoretic mobilities. The mobilities were independent of pH after the reaction at 250° to 300°C for 240 h, indicating that the surface is not hydrated. Refluxing of the powders in water for 170 h brought about a pH dependence of mobility, indicating hydration of the surface.     

EHD-Enhanced Water Evaporation from Partially Wetted Glass Beads with Auxiliary Heating from Below

Earlier studies have shown that an electric field in the form of corona wind can significantly enhance drying rate. It is particularly effective in the early stage of drying when the material is fully wetted. However, the effectiveness of corona wind in drying a partially wetted material, which is commonly believed decreasing, has not been critically examined. For the present study, enhancement of water evaporation from partially wetted glass beads by corona wind is experimentally evaluated. In addition, auxiliary heating provided by a thermofoil heater attached to the bottom surface of the sample container has been used as a possible means to maintain the effectiveness of corona wind. For the present study, a fine copper wire with a diameter of 0.5 mm is used as the emitting electrode. It is charged by direct current with negative polarity from the corona threshold voltage until the occurrence of sparkover. The water level inside the glass beads is below the external surface and is maintained constant in each set of experiments. For each case, a companion experiment is carried out simultaneously under the same ambient conditions but without the application of electric field or auxiliary heating, the result of which is used as a basis in the evaluation of the evaporation enhancement. The weight loss of water as well as the ambient temperature and humidity are continuously monitored. Each experiment lasted for at least 5 h. The results show that the electric field is effective in the enhancement of water evaporation from partially wetted glass beads, but its effectiveness diminishes when the water level in the glass beads recedes. By applying auxiliary heating, this shortcoming of EHD-enhanced drying can be overcome.     

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.     

Study of Composition of Leached Glass Surfaces by Photoelectron Spectroscopy

The effects of water attack on the surfaces of 2 bulk glasses, including changes with time of exposure to air after water exposure, were determined using X-ray photoelectron spectroscopy. Although the layer explored was extremely thin (∼30 Å), this nondestructive technique has potential for quantitative analysis. The results obtained for an industrial glass and an experimental nonresistant one are compared, i.e. the rapidity of ion exchange at the glass-water interface, fluctuation of Na content in the glass surface during water exposure, migration of Na through the SiO₂ surface layer, and nonmigration of Ca under the same conditions. The present results agree with those obtained by other workers from solution analysis and other surface-sensitive physical techniques. The surface of lead crystal glass exposed to dilute acetic acid was also studied.     

以氯化铵和水玻璃生产白炭黑的研究

介绍了以农用氯化铵与工业水玻璃反应 ,生产高比表面积透明活性白炭黑的反应原理、生产方法、工艺线路的选择及工艺指标的确定 ,所得产品收率 96% ,经济效益可观     

玻璃与水的相互作用过程和机理探索

玻璃经常在溶液或者潮湿环境下使用,水的侵蚀会影响玻璃的物理和化学性质,甚至导致玻璃失效。近年来,通过采用多尺度计算机模拟方法,对简单玻璃体系与水相互作用过程和分子尺度反应机理的认识取得了较大进展。本文聚焦石英玻璃、钠硅玻璃和钠硼硅玻璃三个简单的模型玻璃体系,在阐明其耐水性起源的基础上,概述了玻璃与水分子相互作用过程和机理的最新进展,对进一步理解复杂体系玻璃的耐水性和开发新的功能玻璃具有重要的参考价值。     

Reaction of HF with Porous Glass

Infrared spectra were used to follow the reaction of HF with porous glass which had been dehydroxylated to various degrees. The fluoridation proceeded smoothly, and the surface hydroxyls were eliminated completely with samples which were not degassed or were degassed mildly (at temperatures up to approximately 500°C) so that appreciable amounts of water and hydroxyls were on the surface before the HF treatment. Samples which had been severely dehydroxylated before exposure to HF behaved differently, and several HF treatments were required to effect complete fluoridation. Experiments suggest that the replacement of hydroxyls by fluoride is negligible at room temperature, the dominant reaction being the formation of B-OH and B-F groups. The latter are unstable at higher temperatures and release HF, so that dehydroxylation can continue after physically adsorbed HF has been desorbed and pumped away.     

Interdiffusion and Phase-Boundary Reaction Between Silicate Glass Surface and Aqueous CsCl Solution

Technical silicate glass samples with fresh fracture surfaces or HF-etched surfaces were treated in aqueous CsCl at 90°C for 10 to 85 min. Reaction profiles were determined quantitatively using a SIMS technique. The Cs₂O concentration at the glass surface increased with increasing time, followed by penetration of Cs⁺ ions into the glass. The profiles can be described assuming a model which contains both a surface phase-boundary process and an interdiffusion process in the glass for which D=5.10⁻¹⁷ cm² s⁻¹.     

乙酸乙酯在水玻璃溶液中的水解反应研究

研究了乙酸乙酯在ＳｉＯ２浓度为１．０ｍｏｌ·Ｌ－１的水玻璃溶液中的水解反应。分析讨论了水玻璃溶液中乙酸乙酯水解反应的特点,并通过气相色谱分析测定乙酸乙酯水解生成乙醇的量,计算了不同反应温度下乙酸乙酯水解反应的速率常数,求得了水解反应的活化能     

水在玻璃表面的润湿性被破坏的一些看法

分析了医药包装瓶内表面产生憎水性的原因，并提出相应的改进措施。     

Leached Layer Formation on Float Glass Surfaces in the Presence of Acid Interleave Coatings

Acid interleave coatings are routinely used in the float glass industry to inhibit corrosion during transport and storage in hot, humid environments. It is well recognized that acid interleave coatings neutralize surface alkalinity, and thereby delay the onset of etching, dissolution, and permanent staining (so-called Stage II corrosion). However, the effect of acid interleave coatings on leached layer formation (so-called Stage I corrosion) has not been reported. For many applications of float glass, the presence of a shallow leached layer may be of little consequence, but in other applications, there can be nanoscale effects on scratch resistance, optical properties, adsorption, adhesion, and interface stability. In this study, complementary techniques of X-ray photoelectron spectroscopy (XPS) sputter depth profiling and infrared reflection spectroscopy were used to evaluate the thickness of leached layers in float glass samples weathered in a controlled manner, both with and without acid interleave coatings applied. The results reveal that acid interleave coatings do, in fact, enhance leaching during both cyclic and static weathering. This confirms that the acid not only neutralizes the alkaline reaction products of weathering but also reacts with the glass itself by ion exchange. The concentration of acid in the coating influences the thickness of the resultant leached layer, but this effect depends on the weathering conditions (cyclic versus static) and the duration of the exposure; boric acid and adipic acid coatings performed similarly. An excellent correlation was found between the more direct method of XPS depth profiling of the sodium leaching profile and the less direct, but perhaps more convenient, method of infrared reflection spectroscopy.     

Studies on Controlling Surface Accumulation of Glucose on Dehydrated Cabbage

Dehydrated cabbage pretreated with glucose before drying can easily become covered with a thin white film of glucose during storage due to glucose transfer from the inside to the surface. Lactose and high-maltose syrup were added as partial substitutes for glucose in the process of the pretreatment using glucose before drying. In both conditions, good results were obtained concerning extending the period needed for glucose accumulation on the surface of the dried product, particularly in the presence of high-maltose syrup. In this work, effects of blanching time and ambient relative humidity during storage on glucose accumulation were also studied. The results show that dehydrated cabbage blanched for 90s and stored in a low-humidity environment displays reduced glucose accumulation on the surface of the products and extends the accumulation time without reducing glucose content from 12 days to 28 days.