| 摘要 |
1,265,554. Seals. ENGELHARD MIN. ERALS & CHEMICALS CORP. 20 June, 1969 [24 June, 1968], No. 31447/69. Heading B3V. [Also in Division C1] The interfaces of an article having at least.two interfaces, one of which: is glass or ceramic, and the other of which is glass, ceramic or metal, are sealed by a sealing layer which comprises or consists of palladium metal or a palladium alloy, the seal having an exposed portion so that, and the palladium being present in an amount such that, the seal may be broken -by exposure to hydrogen which converts the Pd from the alpha to the beta phase The layer may be of palladium or an alloy having an expansion characteristic in hydrogen similar to palladium, or the palladium or alloy may be dispersed in a fused inorganic non-metallic sealant layer, the layer preferably comprising over 60% by weight of palladium. Further layers of fused inorganic sealant may separate the palladium layer from one or both interfaces with the proviso that there must be present such a layer between the Pd-layer and a metal interface. These further layers may be of the same or different material as that in the palladium layer, and may be 0À0002-0À02 inch thick compared with 0À0001-0À001 inch thick for the palladium layer. The fused inorganic sealing layers may be of a conventional sealing material, examples of which are given, e.g. lead borate, glass, ceramic or glass containing ceramic or refractory material (e.g. zirconium diboride). The palladium alloy may be Pd-Cu, Pd-Pt, Pd-Rh, Pd-Ir, Pd-Os, Pd-Ag. The seal is formed by, for example, forming the Pd layer on an interface, forming a glass frit layer on the other -interface, assembling and firing, at, e.g. 600‹ C. for a glass sealant or 1000‹ C. for a ceramic. Alternatively, the parts can each first be fired before assembling. The seal is broken by exposing the seal to hydrogen (e.g. a 7% H 2 /93% N 2 gas), evidently by converting from theα- to the #-phase, and the seal breaks. The interfaces can be re-sealed if the parts are fired to reconvert the Pd to theα- form and re-assembled as before. |
