| 摘要 |
<p>1514317 Homogenizing or refining glass SAINT-GOBAIN INDUSTRIES 11 Aug 1975 [14 Aug 1974] 33381/75 Heading C1M Molten glass is homogenized and/or refined by heating the glass so that its viscosity is not more than 1000 poises, foaming the molten glass to a volume at least 1À5 times its original volume, and maintaining the viscosity at not more than 1000 poises until the foam collapses. Preferably the glass is foamed by a gas-generating agent (e.g. Na 2 SO 4 ), the molten glass being heated at at least 20‹C. per minute. The foaming may be aided by ultrasonic vibrations. Preferably, solid vitrifiable material in granular or agglomerated form is passed to inclined duct 14 via furnace 13, in each of which the material is melted by burners 20 and 21. Gases from burners 20. 21 pre-heat the solid material in heat exchanger 23. Furnace 13 and duct 14 are cooled through tubes 17. The molten material formed is passed to channel 1 formed of Pt-Rh alloy, and surrounded by alumina insulation material 12. 12a. The molten material is heated, by Pt-Rh electrode 2 (which may be water-cooled) and by Pt-Rh immersed resistance electrode 10, at at least 20‹C./minute so that the molten glass is foamed and collapses before being delivered through tube 6. In a preferred embodiment granules are heated to 1300‹C. in 6 minutes, from 1300‹C. to 1500‹C. at 30‹C./minute, and held at 1500‹C. for about 10 minutes. In an alternative embodiment (Figures 3 and 4, not shown) the channel is supplied with molybdenum electrodes.</p> |
