GB999184A - Improvements relating to the bonding of metals - Google Patents

Abstract

999,184. Welding by pressure; brazing. INTERNATIONAL NICKEL Ltd. Oct. 15, 1962 [Oct. 17, 1961], No. 37191/61. Addition to 919,031. Heading B3R. In joining two metal pieces by heat and pressure to form a bond by metallic diffusion as claimed in the parent Specification, wherein the pieces are maintained slightly separated within a sheath which is deformable under welding pressure and with the pieces forms an air-tight assembly enclosing the surfaces to be joined, the assembly is heated and pressure is applied to close the gap and deform the sheath while the atmosphere in the interior of the sheath is reactive and capable of dispersing or destroying acids films or is inert and protective or is exhausted, a thin layer of palladium containing brazing alloy in foil or powder form is interposed between the pieces. The brazing alloy may be the ternary alloys of nickel, palladium and manganese defined in Specification 742,820, the ternary alloys of copper, palladium and manganese defined in Specification 838,950, the ternary alloys of copper, palladium and nickel defined in Specification 838,951 and the-quaternary alloys of copper, palladium, nickel and manganese defined in Specification 838,949. When the metal pieces are heated the brazing alloy melts and when pressure is applied contact is established between the metal pieces, any discontinuities at the interface are filled with brazing alloy and excess brazing alloy is squeezed from the joint. The pieces to be joined may be of 18-21% chromium, 15-21% cobalt, 1À8-3À0% titanium, 0À8-2À0% aluminium, up to 5% iron, small quantities of silicon, manganese and carbon and the balance nickel, joined in a protective atmosphere at 1200‹ C. under a pressure of 2 tons per sq. inch, with an interlayer of an alloy containing 48% nickel, 31% manganese and 21% palladium. The joint is subjected to heating to cause further diffusion at the joint.