| 摘要 |
1,147,830. Making glass. CORNING GLASS WORKS. 29 Dec., 1967 [29 Dec., 1966; 13 Nov., 1967], No. 59040/67. Heading C1M. A glass having a low water-content is made by mixing in the batch a chemically reactive chlorine-containing compound, and melting with a dry atmosphere flowing directly over the melt. The compound is anhydrous and normally a solid stable up to 100‹ C., and may be a chloride of Li, Na, K, Rb, Cs, Tl, Ag, In, Au, Be, Mg, Ca, Sr, Ba, Zn, Cd, Pb, Hg, Ga, Zr, Sn, Te, Al, Sc, Ti, Y, La, Bi, Sb, Se, Hf, Nb, Mo, Ta, or W. Preferable chlorides are those of alkaline earth metals, Zn, Cd, Pb, or Al. 3-10 moles per cent CaCl 2 may be used. The batch is melted at 1500-1650‹ C. Base-glasses include calcium aluminosilicate, calcium aluminogermanate, soda-lime, borosilicate, lead glass, germanate, and tellurite glasses. The method cannot be used for fused silica or 96% silica glasses. During melting Cl atoms from the compound displace OH groups in the glass network. Water formed during this reaction is removed by the dry atmosphere, e.g. air, N 2 , He, Ar, O 2 , CO 2 , or SO 2 . Glasses made by this method include I.R.-transmitting glasses and glasses for lamps, e.g. for the envelopes of high-temperature vapour lamps.
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