| 摘要 |
<PICT:1049922/C1/1> In a method of locally maintaining extended glass articles such as glass filaments, tubes or sheets, either wholly or in part, in a given atmosphere during the course of manufacture, liquid seals are provided, which do not substantially wet the glass at the temperatures involved. The liquid may be mercury, a molten metal or metal alloy, e.g. tin, or a molten metal oxide, e.g. vanadium or lead. The atmosphere is preferably free from water vapour and may be used to isolate the glass from external atmosphere, to form a metallic deposit on the glass surface, or to exert some chemical action, such as de-alkalizing, to alter the surface properties. In the case of oxidizable metals the atmosphere is either inert or reducing. In the production of glass filaments as described in Example 1 the filaments A (Fig. 1, not shown) formed at the bushing 1a pass through a chamber 8 which has a liquid seal of mercury 12 at the exit end. A dry inert gas (e.g. argon) is passed through drying tubes 15, 16 and distributer 14 into the chamber 8 and out through distributer 17. This permits the glass filaments to cool without being attacked by water vapour. In Example 2 a glass tube 22 is upwardly drawn through a series of interconnecting chambers 28, 33 provided with liquid seals 38, 39, 40 which may be heated. In this example aerosols of stannic tetrachloride and chromylchloride in glacial acetic acid, the latter at temp. of 500 DEG to 700 DEG C., are caused to flow through the chambers 28 and 33 respectively to form, on the tube, coatings of stannic oxide followed by chromic oxide of definite thicknesses and electrical conductivity. In Example 3 a glass sheet 41 (Fig. 3, not shown) is passed over a bed of graphite and is supported thereon by strips 43 of liquid in troughs 44. The strips 43 of liquid form seals and define isolated zones into which gases may be passed, say two alternately, for building up on the lower face of the sheet a series of superimposed coatings to form an interference filter.
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