Factors of Surface and Volumetric Reactions in Glass Technology Processes

Various phenomena and processes in glass production are considered taking into account surface and volumetric factors. Kinetic analysis of reactions of K₂O – PbO – SiO₂ system glasses with a reducing flame and the molding process under isothermal and non-isothermal conditions is carried out. The data obtained can be used for analysis and calculations of technological processes.     

Flow Microcalorimetric Estimation of Energy Changes During Surface Reactions of Glass Powders with Aqueous Media

Flow microcalorimetry was used for an investigation of the surface chemical nature of glass surfaces. A commercially available flow microcalorimeter allowed for the measurement of heat energy changes during surface reactions of two different glass powders with pyridine and water solutions. Pure fused silica glass and a fluorozirconate glass were the materials studied by flow microcalorimetry.     

锌磷酸盐玻璃水解实验研究

为了探索锌磷酸盐玻璃的化学稳定性,通过浸泡加速水解实验观察了玻璃样品与水作用前后的变化。利用XRD、SEM、FT-IR和Raman等技术分析了玻璃样品的结构和微观形貌,结果表明,采用传统熔融冷却法制备的50ZnO-50P_2O_5玻璃,微观网络结构主要为Q~2结构单元;分别浸泡20天和30天,锌磷酸盐玻璃微观网络结构解体,形成了(ZnHPO_4)_2·3H_2O和Zn_2P_2O_7·3H_2O晶体,随着浸泡时间增加,玻璃体系转化为Zn_2P_2O_7·3H_2O晶体。     

Chemical Durability of Fluorozirconate Glasses

The chemical durability of four fiuorozirconate glasses was tested in distilled water at 20° and 80°C. Overall dissolution of the glasses, obtained from weight losses, followed a nearly perfect t^1/2 dependence, and evidence for an F^-/OH^- ion exchange between glass and solution was found. These observations, however, do not necessarily imply a simple diffusion-controlled process. All surfaces were cracked and showed crystalline deposits of differing composition. A protective layer did not form on the surface.     

Heats of Fusion of Fluorozirconate Systems

The heat of crystallization of a glass obtained by an isothermal DSC experiment does not represent the true value of the heat of fusion. A procedure is described to evaluate the heat of fusion from measured values of heats of crystallization. The correction term is estimated to be as important as the measured values of heats of crystallization in the case of fluorozirconate glasses.     

Surface Composition of Porous Glass

Both boron and silicon were detected on the surface of porous glass. Infrared and adsorption data show five or six times more boron in the surface than can be expected from chemical analysis of the porous glass. It is suggested that the excess of boron in the surface occurs during the leaching of the base glass.     

Nitriding of Industrial Glass Surface

The effect of gas-thermal nitriding of window, medical, electrovacuum, and crystal glass surfaces on the service properties of glass is investigated. The hydrophoby, water resistance, microhardness, impact viscosity, and heat resistance of glasses are analyzed depending on the duration of nitriding involving different nitrogen-bearing gas reactants. Technological recommendations for gas-thermal nitriding of glass articles in industrial conditions are issued.     

Fracture Surface Energy of Glass

Fracture surface energies of six glasses were measured using the double-cantilever cleavage technique. Values ranged from 3.5 to 5.3 J/m² depending on the chemical composition of the glass and the temperature of the test. The fracture surface energy increased with decreasing temperature and increasing Young's modulus; however, exceptions to this behavior were noted. The magnitude of the values obtained is discussed with respect to the theoretical strength of glass and possible irreversible effects at the crack tip such as stress corrosion and plastic deformation are considered.     

The Role of Cations in Some Inorganic Hydrolysis Reactions

Cations which shift certain equilibria from left to right by forming a compound with one of the reaction products were investigated with respect to their kinetic role in the process. Silver ions have no influence on the rate of the hydrolysis of cyanogen iodide. Similarly, cations which form sparingly soluble carbonates do not influence the rate of hydration of carbon dioxide. On the other hand, the hydrolysis of chlorine is accelerated by Ag⁺ and, to a lesser extent, by Cd²⁺ and Fe(III). It is shown that the effect is not due simply to a bimolecular reaction between chlorine and the cation. In the case of Ag⁺, heterogeneous catalysis may play some role, in analogy with the solvolysis of organic halides. In the case of Cd²⁺, there is spectrophotometric evidence for compounds between Cl₂ and HOCl on the one hand, and the cation on the other. It is suggested that these compounds interconvert more rapidly than do the parent substances. A similar mechanism may be operative in the case of Fe(III), and, possibly, also in the case of Ag⁺.     

Modeling of Temperature-Programmed Surface Reactions

Temperature-programmed surface reaction (TPSR) experiments with a ruthenium-based catalyst supported on MgO were conducted in a microreactor flow system. The hydrogenation of preadsorbed atomic nitrogen obtained under various experimental conditions has been studied followed by a detailed microkinetic analysis including an evaluation of the influence of backmixing. The shape of the TPSR profile was found to depend strongly on the initial surface coverage and on the presence of coadsorbates.     

玻纤增强PBT的耐水解性能的研究和优化

系统地研究了抗水解剂聚碳化二亚胺、扩链剂SAG系列、阻隔树脂EVOH对玻纤增强PBT的力学性能、加工性能以及耐水解性能的影响。结果显示:PBT的耐水解性能随着抗水解剂含量增加而提高,高-N=C=N-浓度的抗水解剂对PBT耐水解性能的提升效果更加显著;多环氧官能团的扩链剂对PBT材料的耐水解性能提升明显,使用环氧含量高的扩链剂,PBT的耐水解性能更优;阻隔树脂EVOH的引入会降低PBT材料初始物理性能,只有当EVOH含量达到一定含量才对PBT耐水解性能起到正向提升作用。在上述研究结果的基础上,通过优化组分和含量,输出耐水解PBT材料配方,其基本物性和耐水解性能与进口材料相当。     

Transformation Range Viscosity of Fluorozirconate Glasses

Transformation range viscosity was measured for multicomponent fluorozirconate glasses in the system 0.56ZrF₄·(0.34-x)BaF₂·0.06LaF₃·0.04AlF₃·xRF, where R =Li, Na, K, or Cs . The results indicate that the viscosity of these glasses can be described by an Arrhenius equation over the viscosity range from 10⁷ to 10¹² Pa·s with an activation energy of the order of 650 to 850 kJ. In general, the effects of alkali fluoride additions on the viscosity of fluorozirconate glasses are comparable to those in silicate systems.     

Chemical Relaxation of Surface Reactions

The study of the rate of self-adjustment of a homogeneous, chemically reacting system that has been perturbed from its thermostatic equilibrium has received much attention recently, and has been very fruitful in unraveling the details of the molecular encounters underlying chemical changes. Of singular interest has been the study     

Quantum-Chemical Justification of the Structure of Fluorozirconate Glasses1

A number of fluorozirconate clusters of the general formula [Zr _m F _n ]^{(4m– n)}and barium fluorozirconate clusters [BaZr₂F _n ]^{(10 – n)}are studied by the quantum-chemical discrete variational X method. It is shown that the mean energies of fluorine ion addition for all structural units observed in real fluorozirconate crystals lies in a narrow range. The vibrational spectra are analyzed within the energy approach. It is demonstrated that the coordination number of zirconium in a number of barium fluorozirconate glasses is equal to seven or eight. The possible mechanism of structural transformations in binary fluorozirconate glass with a variation in its composition is proposed. The rigidity of different bonds in fluorozirconate clusters is investigated qualitatively. It is established that the rigidities of zirconium bonds with bridging and terminal fluoride ions level off in polymers, which is a prerequisite for the glass formation in fluorozirconate systems.     

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     

功能化离子液体催化水解反应的研究

以离子液体PEG1000-DAIL为基础合成了不同阴离子的功能化离子液体,发现了功能化离子液体与甲苯形成良好的温控两相体系,并研究了它们在有机卤化物、环氧化合物和酯类化合物的水解反应。实验表明,以Fe2(SO4)3为辅助催化剂,以PEG1000-DAIL[OTf]为主催化剂下,有机卤化物的水解反应效果最好,水解产物收率在97%。以PEG1000-DAIL[OTf]为主催化剂下,以Cu SO4为辅助催化剂,环氧化合物水解反应效果最好,其水解产物收率达到93%。以PEG1000-DAIL[OTf]为主催化剂下,以Fe2(SO4)3为辅助催化剂,酯类化合物水解反应效果最好,其水解产物收率达到91%。离子液体和辅助催化剂重复使用时,经重复使用五次,其催化性能没有明显的变化。