GB842158A - Process of casting titanium and related metal and alloys and apparatus therefor - Google Patents

Abstract

842,158. Casting-processes. MISCO PRECISION CASTING CO. May 7, 1957, No. 14574/57. Class 83 (1). [Also in Group XI] When casting metals of Periodic Group IVA or alloys thereof, the mould cavity is lined with a thin film of a metal of Group IVA or an alloy thereof, which barrier film protects the molten metal from reaction with the mould material. The film, preferably between 0.0003 and 0.000001 inch thick, may be vacuum-deposited on a pattern for transference to a shell mould, or on a destructible pattern for lining an investment mould. It may have an outer layer or layers of a metal of good heat-conductivity, such as Cu, Cr, Ni, Fe, Co, applied by electrodeposition &c., to a thickness of 0.001-0.005 inch, the layer or layers serving by chilling to prevent breakdown of the barrier film by the melt. The layer or layers may be removed from the cast article, or retained as a protective layer. An investment mould 11a having a titanium barrier film 13 and an outer layer, 14, has shot 15 at the bottom for additional chilling effect. The mould is mounted within an inductive heating coil 37, Fig. 5, in a chamber 30, which is filled with inert gas. Above the mould is mounted a crucible 34 within a heating coil 36, which melts the upstanding portion 34d, the molten pool created thereby melting the plug section 34a and flowing into the mould. A pressure differential above and below the crucible may assist the flow. In a modification, Fig. 7, titanium is melted by induction heating in an evacuable chamber 21, which is tilted to pour the melt into the inductively-heated mould 11 supported by clamps 34, 35, in an extension to the chamber. When casting alloys of a metal of said group, the barrier film need not be of the same alloy, but may be of the pure metal of the group, or a different alloy of said metal.