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Foaming and fining behavior in glass melts.

机译：玻璃熔体中的起泡和澄清行为。

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摘要

The foaming behavior of various glasses was studied using a direct observation method and an electrical probe method. The experimental results showed that two distinct foaming processes existed during glass melting: the primary foaming caused by the decomposition of carbonates, and the high temperature foaming caused by the redox reactions and gas oversaturation in the glass melts. Among many fundamental properties affecting foaming behavior, the volatilization and surface tension were studied. The volatilization at the glass melt surface greatly increases the viscosity and increases the stability of the foam. Water vapor highly enhances the weight loss of the glass melt. At very high temperatures, the rapid depletion of alkali on the surface will form a silica-rich layer which is a diffusion barrier for further alkali loss. Surface tension decreases with increasing water vapor content in the atmosphere.; Foaming in the glasses with Na2SO4, fining agent is caused by the decomposition of sulfate at high temperature. The solubility of SO42- groups decreases as temperature increases, and oxygen and sulfur dioxide gases release from the melt. Foam forms when the oversaturation is high enough and the gas release is aggressive. Al 2O3 and Li2O decreases the foaming temperature because they decrease the solubility of sulfate due to their unique role in the glass structure. However, the substitution of Na2O by K 2O increases the foaming temperature. The compositional effects are also explained by the relationship between the sulfate and gas solubility and the basicity of glass melt. When Sb2O3, As 2O3, and CeO2 are used as fining agents, the high temperature foaming is caused by the oxygen release from the redox reactions of the multivalent fining; agent ions in the glass melt. A combined fining agent of antimony, arsenic, or cerium oxide and sodium sulfate shows a reduced foam volume for both high temperature and primary foaming, providing a potential route to control the foaming process in glass melting. The mechanisms for this foaming reduction are believed to be the decrease in the dissolution rate of silica sand grains and the modification of the gas diffusion in the glass melt. It was shown that the fining efficiency of the glasses could be increased by combining the fining agents.; Water vapor affects the redox reaction of sulfur in glass melts and decreases the solubility of sulfate, thus decreasing the foaming temperature when only Na2SO4 is used as fining agent. The considerable increase in maximum foam volume is ascribed to the fact that water accelerates the volatilization of the glass melt and increases the viscosity of glass melt in the bubble walls. For the Sb2O3 fined soda-lime-alumina-silica glasses, oxygen can slightly increase the maximum volume of the high temperature foam and makes its decay slower. Water vapor also increases the maximum foam volume and decreases the decay rate. The mechanisms of water effects are discussed based on the volatilization of glass melt and redox reactions of antimony ions. For the sulfate fined soda-lithia-lime-alumina-silica glasses, the foam stability was considerably reduced by changing the atmosphere from CO 2 + 50%H2O to other dry atmospheres. The stability of the foam in the antimony-fined SLAS glasses also showed a decrease when the above atmosphere change was made. The mechanisms were proposed based on the gas diffusion sulfate redox reaction, and water release from glass melt due to the atmosphere change.
机译：使用直接观察法和电探针法研究了各种玻璃的起泡行为。实验结果表明，玻璃熔融过程中存在两种截然不同的发泡过程：由碳酸盐分解引起的初次发泡，以及由玻璃熔体中的氧化还原反应和气体过饱和引起的高温发泡。在影响发泡行为的许多基本特性中，对挥发度和表面张力进行了研究。玻璃熔体表面的挥发大大增加了粘度并增加了泡沫的稳定性。水蒸气极大地增加了玻璃熔体的重量损失。在非常高的温度下，表面上碱的快速消耗将形成富含二氧化硅的层，该层是进一步碱损失的扩散屏障。表面张力随着大气中水蒸气含量的增加而降低。用Na 2 SO 4在玻璃中起泡，澄清剂是由高温下硫酸盐的分解引起的。 SO42-基团的溶解度随温度升高而降低，氧气和二氧化硫气体从熔体中释放出来。当过饱和度足够高并且气体释放剧烈时，就会形成泡沫。 Al 2O3和Li2O由于在玻璃结构中的独特作用而降低了硫酸盐的溶解度，因此降低了发泡温度。但是，用K 2O取代Na2O会增加发泡温度。还通过硫酸盐和气体溶解度与玻璃熔体的碱度之间的关系解释了组成效应。当Sb2O3，As 2O3和CeO2用作澄清剂时，高温起泡是由于多价澄清的氧化还原反应中释放的氧气引起的。离子在玻璃中融化。锑，砷或氧化铈和硫酸钠的混合澄清剂在高温和初次发泡时均显示出减少的泡沫体积，为控制玻璃熔融中的发泡过程提供了一种可能的途径。据信这种减少泡沫的机理是硅砂颗粒溶解速率的降低和玻璃熔体中气体扩散的改变。结果表明，通过结合澄清剂可以提高玻璃的澄清效率。水蒸气会影响玻璃熔体中硫的氧化还原反应，并降低硫酸盐的溶解度，因此当仅使用Na2SO4作澄清剂时会降低发泡温度。最大泡沫体积的显着增加归因于以下事实：水加速了玻璃熔体的挥发并增加了气泡壁中玻璃熔体的粘度。对于用Sb2O3细化的钠钙铝硅玻璃，氧气会稍微增加高温泡沫的最大体积，并使其衰减变慢。水蒸气还会增加最大泡沫体积并降低衰减率。基于玻璃熔体的挥发和锑离子的氧化还原反应，讨论了水效应的机理。对于用硫酸盐精制的钠钙钙铝硅玻璃，通过将气氛从CO 2 + 50％H2O改为其他干燥气氛，泡沫稳定性大大降低。当进行上述气氛改变时，锑制SLAS玻璃中泡沫的稳定性也显示出降低。根据气体扩散硫酸盐的氧化还原反应，以及由于大气变化而从玻璃熔体中释放水，提出了机理。

著录项

  • 作者

    Jiang, Haochuan.;

  • 作者单位

    Alfred University.;

  • 授予单位 Alfred University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1999
  • 页码 183 p.
  • 总页数 183
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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