| 摘要 |
1,152,134. Ceramic-metal seals. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 27 Nov., 1967 [30 Nov., 1966], No. 53820/67. Heading B3V. [Also in Division H1] A method of making a vacuum-tight joint between a metal article and ceramic parts comprises clamping the metal article between two or more ceramic parts at a pressure less than 150 kgs./sq. cm. and heating it in an atmosphere of dry hydrogen until the metal has adhered direct to the ceramic material, the ceramic material being alumina and the metal of the metal article, at least at its surface, being of one of the group: iron, platinum, cobalt and nickel. As applied to sealing a current supply conductor 4 in the alumina envelope 1 of an alkal f metal, e.g. sodium, discharge tube, the core o the conductor 4 may consist of an alloy, e.g. of Fe-Ni-Co, the coefficient of expansion of which is adapted to that of the ceramic. An iron or molybdenum cylinder 3 is welded to the conductor 4 which is then sealed to a sleeve 5 and a disc 6 of alumina by the above method at a temperature of 1375‹ C and a pressure of 15 kgs./sq. cm. An electrode 2 is then secured to the cylinder and the conductor sealed to the envelope 1. The parts may be pre-assembled before the envelope 1, sleeve 5 and disc 6 are sealed to the conductor 4 in a single operation. The heating temperature may be 90% of the melting temperature of the metal. In a further form, Fig. 2 (not shown), a tapered conductor (11) is clamped between tapered alumina sleeves (9, 10) and sealed thereto, a vitreous seal (13) being used between the outer sleeve (10) and the envelope (1). |
