| 摘要 |
1,054,753. Glass composition; glass seals. GENERAL ELECTRIC CO. March 9, 1964 [March 14, 1963], No. 9847/64. Heading C1M. [Also in Division B3] A glass is composed by weight of about 40% B 2 O 3 , 25% Al 2 O 3 and 35% BaO and the mean coefficients of thermal expansion of the glass in the range 20-500‹ C. differ from that of Ta at the same temperature by not more than 10 x 10<SP>-7</SP>/‹ C., and the glass may be sealed to Ta and other metals, alloys and ceramics. A suitable batch composition is in parts by weight: BaCO 3 , 45À1; Al(OH) 3 , 38.3; and H 3 BO 3 , 71À1. After the batch is melted, the glass is chilled on a cold metal plate. To make a seal, in a preferred method, the glass is then crushed and milled to- 100 U.S.S. sieve size, mixed with binder comprising butyl methacrylate diluted with trichlorethane and including as lubricant a powdered vegetable stearine. After mixing and drying, the glass is crushed, and annular pellets are pressed therefrom, heated at 400‹ C. to volatilize the binder, and sintered at 660‹ C. Glass to metal seals may be made with Ta, preferably pre-oxidized, Nb, and Ni/Fe and Ni/Co/Mu/Fe alloys and Ti. Thus in Fig. 2, Ta wire 1, glass annulus 2 and Ti header 3 resting on graphite pedestal 4a and covered by graphite cap 46 are heated by induction coil 5 in Ar to 1075‹ C., or are heated in vacuo to 650‹ C. and then in Ar to 875‹ C.; the assembly is then cooled in Ar. The assembly may then be incorporated into an electrical device (Fig. 3, not shown). Alumina to glass to metal seals, wherein the alumina is mono or poly-crystalline and particularly for sapphire windows, may be made in the same manner as the glass-to-metal seals above. |
