GB449753A - Improvements in or relating to the production of wear-resisting metallic articles - Google Patents

Abstract

Wear-resisting articles for use as tools, dies, sand blast nozzles, contact points, well borers, and for other purposes, are made by alloying one or more carbide-forming metals such as tungsten, tantalum, titanium, zirconium, molybdenum, chromium, thorium, and rhenium, with one or more metals of lower melting point such as iron, manganese, nickel, cobalt, silver, and copper, carburizing or carburizing and boronizing the alloy so formed, powdering the product, mixing powdered metallic bonding material therewith, and bonding the constituents by heat-treatment. The bonding material may be an iron-group metal which may be mixed as oxide with the powdered alloy, the oxide being subsequently reduced. A preferred composition is a carburized or carburized and boronized alloy of tungsten and one or more iron-group metals bonded as described. Alloys of refractory metals and the other metals referred to are powdered and heated with carbon or carbon and boron; the products are finely powdered and mixed with oxides of iron &c. heated in hydrogen, pressed to shape, and further highly heated, with or without pressure, in a carbonaceous, hydrogen, or reducing atmosphere. In making the alloys, compounds such as cobalt oxide, iron oxide, and thorium nitrate, or cobalt tungstate, iron tungstate, and tungsten oxide may be used, the mixed powders being reduced in hydrogen. The carburizing may be effected by mixing the alloy powders with lamp black and heating to about 950 DEG C. in hydrogen, crushing and milling the product and reheating to about 1250 DEG C. in a carbonaceous, hydrogen, or reducing atmosphere. If boronizing is to be effected, boron suboxide or boron nitrate is used along with the lamp black. The product is powdered and mixed with bonding material such as cobalt oxide and reduced in hydrogen at about 350 DEG C. It is afterwards shaped by pressure in moulds or by being mixed with an organic binder such as starch paste, gum arabic, caramel, or casein solution and extruded, the pieces being baked and then highly heated. The final product may contain 57,5-92,5 per cent of refractory metals, 0,25-5 per cent of iron, 0,25-2,5 per cent of chromium and thorium, 5-10 per cent of carbon and boron, and 2-25 per cent of cobalt and nickel. Specification 449,847 is referred to.