GB866071A - Articles made of refractory metals and alloys - Google Patents

Abstract

An article made of molybdenum, tungsten, niobium, tantalum, chromium, or an alloy thereof, has an outer coating containing beryllium and nickel, cobalt, or iron. Gas turbine parts, e.g. rotor or stator blades, or furnace components, e.g. heating tubes, of high temperature boilers, may be so coated. A suspension in xylene of a powdered eutectic alloy of beryllium with iron, nickel or cobalt may be applied to the article, which is then dried and heated to 1200 DEG C in an electric resistance or induction furnace to fuse on the coating, or the article may be dipped in the molten beryllium alloy in an inert atmosphere. Alternatively the article may be initially coated with nickel, cobalt, or iron by electroplating, rolling, spraying, vacuum sputtering, or vacuum evaporation and then coated with beryllium (a) by heating with powdered beryllium in vacuum or an inert atmosphere; (b) by heating in an atmosphere containing a beryllium halide and argon or helium; (c) by heating in an air-free vessel with a mixture of powdered beryllium or beryllium alloy ammonium chloride, and beryllia, magnesia, or thoria; or (d) by electrolytic deposition at a high temperature from a molten bath consisting of a mixture of beryllium fluoride or oxyfluoride and sodium or barium fluoride or oxyfluoride. The Provisional Specification refers to a coating consisting of an alloy of beryllium and one of the metals of which the article may be formed.