Patent GB-1066673-A (GB)
Title: Sinterable films
IPC: C03C29/00
Filed: 1964-04-28
Abstract: A self-supporting film comprising particles of a fusible, heat-softenable or sinterable material homogenously dispersed in a soluble organic binder is bonded to a surface by heating the assembly to remove the binder and bond the particles to each other and to the surface, the fusion, softening or sintering temperature of the said particles being above the volatilisation of decomposition temperature of the binder.  The method has particular application in the formation of glass-metal, glass-ceramic, glass-glass, ceramic-metal and ceramic-ceramic seals.  The self-supporting film may be composed of fine particles of metal, metal oxide, metal hydride, brazing alloy or glass homogeneously dispersed in an organic binder such as ethyl cellulose, nylon, polyvinyl alcohol, polymethyl methacrylate, methyl cellulose or hydroxyethyl cellulose and including butyl carbitol as a temporary plasticizer and ethylene carbonate. The glass particles may be those such as Corning 7052.  The metals may be molybdenum, tantalum, rhenium, iron manganese, aluminium, titanium, zirconium and copper or alloys thereof, e.g. Cu-Ag brazing alloys or the oxides or hydrides thereof including nickel, which are reduced to metal during sintering.  Metal-to-metal seal.  A copper surface was brazed to a copper surface by placing a self-supporting brazing film (the brazing alloy being composed of 60% copper, 40% silver) between the two surfaces and the assembly fired at 830 DEG C.  The actual bond is formed by a entectic mixture which occurs at 780 DEG C.ALSO:A self-supporting film comprising particles of a fusible, heat-softenable or sinterable material homogeneously dispersed in a soluble organic binder is bonded to a surface by heating the assembly to remove the binder and bond the particles to each other and to the surface, the fusion, softening, or sintering temperature of the said particles being above the volatilization or decomposition temperature of the binder.  The method has particular application in the formation of glass-metal, glass-ceramic, glass-glass, ceramic-metal and ceramic-ceramic seals.  The self-supporting film may be composed of fine particles of metal, metal oxide, metal hydride, brazing alloy or glass homogeneously dispersed in an organic binder such as ethyl cellulose, nylon, polyvinyl alchol, polymethyl methacrylate, methyl cellulose or hydroxyethyl cellulose and including butyl carbitol as a temporary plasticizer and ethylene carbonate.  The glass particles may be those such as Corning 7052.  The metals may be molybdenum, tantalum, rhenium, iron manganese, aluminium, titanium, zirconium and copper or alloys thereof, or the oxides or hydrides thereof including nickel.  Examples of the use of this method are given. Glass-to-metal seal.-A metal surface (e.g. a nickel-cobalt-iron alloy) was heated to 650 DEG  C. to form an oxide layer on the surface. A self-supporting film of particulate glass in a binder was adhered to the metal surface using a solvent and the assembly heated to 1000 DEG  C. to drive off the binder and form the bond. A glass tube was then fused to the glass layer to complete the seal.