| 摘要 |
1,110,706. Ceramic to metal seals. UNITED STATES ATOMIC ENERGY COMMISSION. 7 March, 1966 [26 March, 1965], No. 9825/66. Heading B3V. A method of bonding a metal to a ceramic comprises disposing a series of layers of a mixture of said ceramic and said metal in powder form between the surfaces to be bonded, the layer adjacent the metal containing a higher proportion of metal powder than ceramic powder and that adjacent the ceramic containing a higher proportion of ceramic powder. Metals such as W, Mo, Zr, Hf, Nb, Ta, Re, Ru, Pd, Pt, Ti, V, Cr or alloys thereof, may be bonded to ceramics, such as BeO, MgO, TiO 2 , ZrO 2 , Y 2 O 3 , HfO 2 , ceria lutetium oxide, ThO 2 , UO 2 , borides, carbides, nitrides, silicides of the above metals and physical or chemical combinations thereof. In an example (Figs. 1 and 2) the ends of two niobium cups are bonded to opposite sides of an alumina disc, using variable gradient layers of alumina-Nb powder between the ends and the disc. Adjacent the ends, the powder may be from 50 to more than 99% Nb. The parts to be bonded are degreased and treated with a solution of nitric, sulphuric and hydrofluoric acids. The intermediate powder can be applied by dusting or spraying layers on to the ceramic or metal surface, or by pressing thin wafers of the desired composition gradient. In place of the ceramic disc a layer of the pure ceramic may be applied on one side of the graded wafers. Included in the powder mixture may be ¢% magnesium oxide. The parts are assembled within a niobium sleeve the ends of which are electron-beam welded in a vacuum to the ends of the cups to form an evacuated assembly which is transferred to a gas pressurefurnace to pressure-sinter and bond the seal assembly. Furnace temperatures, pressures and atmospheres are referred to. Alternatively, the seal assembly may be formed by hot pressing in a punch-and-die unit under vacuum if the assembly is not encapsulated. A circumferential slot is cut through the outer sleeve. Leadin seals may be formed. |
