A study of refining. Part 2: Mechanisms of refining
A study of refining. Part 2: Mechanisms of refining
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DOI：
10.13036/17533546.57.6.205
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发表时间：
2016-12-01
影响因子：
0.3
通讯作者：
Cable, Michael
中科院分区：
文献类型：
--
作者：
Cable, Michael
结果表明，熔体中气泡的上升不能解释第一部分中报告的精炼行为，特别是小种子的消失。然后考虑另外两种可以除去种子的机制。合并似乎只在融化的最初阶段很重要，然后注意力转向气泡的增长或收缩，这是由于气体在其边界上扩散。导出了一个球形气泡的理论表达式，给出了直径作为时间、溶解度、扩散率和熔体中一种气体饱和度的函数。考虑了表面张力对气泡内部压力的影响，但忽略了边界运动引起的浓度梯度畸变。利用假设的溶解度和扩散率对氧气和二氧化碳进行数值计算，表明氧气和二氧化碳的扩散至少可能足够快，在精炼过程中起重要作用。引用了支持这一结论的其他数据。得出的结论是，有两种机制支配着玻璃在非批量时间之后的精炼，即大种子上升到熔体表面和小种子溶解，但目前还不能对观察到的结果给出定量的说明。
It is shown that rise of bubbles through the melt is unable to account for the refining behaviour reported in Part I, particularly the disappearance of small seed. Two other mechanisms whereby seed may be removed are then considered. Coalescence seems to be important only in the earliest stages of melting and attention is then turned to the growth or contraction of bubbles due to gas diffusing across their boundaries. A theoretical expression is derived for a spherical bubble giving the diameter as a function of time, the solubility, diffusivity, and saturation of one gas in the melt. The effect of surface tension on the pressure inside the bubble is taken into account but the distortion of the concentration gradient caused by the motion of the boundary is ignored. Numerical calculations for oxygen and carbon dioxide, using assumed solubilities and diffusivities, indicate that diffusion of the former at least is probably sufficiently rapid to be important in refining. Other data supporting this conclusion are cited. It is concluded that two mechanisms governed the refining of the glass beyond the batch-free time, the rise of large seed to the surface of the melt and the dissolving of small seed, but it is not yet possible to give a quantitative account of the observed results.