| Summary: | 碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 103 === The homogeneity of glasses is important to their physical properties, and hence, homogenization of the melt is a critical step in glass production. Glasses are produced by melting and chemical reaction of batch oxide components at an elevated temperature. Inhomogeneity is complex, influenced and determined by several factors such as bubbles, striae, stones. The inhomogeneities which are the regions of slight compositional difference, it can exhibit different indices of refraction from the bulk of the glass. The inhomogeneities may be present in the molten glass due to delayed melting of some raw materials, or due to erosion of refractory walls, or by vaporization of volatile constituents, or substances added to the glass after melting.
Therefore, a mathematical model with the flow pattern of molten glass in the stirrer tank was established. The influence of different stirred designs (Ns: number of screw resolution, Ds/D: the size of screw, ω: rotating speed) were simulated and discussed. Moreover, the influence of the behavior of flow motivation and inhomogeneities distribution in different stirred designs were analyzed by Taguchi methods. Homogeneity is composed by the four factor which are vortex factor (causing circulation to molten glass on stirrer tank), the average particle path length (causing spreading to molten glass on stirrer tank), the maximum difference of concentration (homogeneity at the same time), FWHM of average concentration (homogeneity within the time).
From results, the influence of Ns and ω are more important than the others. The homogeneity of molten glass is best in screw-5 which is Ns=2, Ds/D=0.6, ω=25 rpm (vortex factor =55.8%, the average particle path length =14529 cm, the maximum difference of concentration =5.0 x 10-5, FWHM of average concentration =1130 s).
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