Method of manufacturing components

Abstract

A method of forming a wear resistant component is disclosed. The method includes the metallurgical bonding of an abrasion resistant alloy to a substrate within a furnace. A gas flow restricting means is used to restrict the flow of gaseous oxygen into the region of the metallurgical bond, allowing a furnace to be used without vacuum extraction.

1 . A method of manufacturing a component, the method comprising the steps of:
 (i) providing an outer shell formed by a first metallic material, the outer shell having a base and side walls defining a cavity, the cavity being open at an upper end thereof;   (ii) providing a second metallic material above the base of the cavity;   (iii) providing a gas flow restricting means to restrict the flow of gas into the cavity;   (iv) heating the first and second metallic materials to above the solidus temperature of the second metallic material so that the second metallic material flows and covers the base of the cavity;   (v) heating the metallic materials above the liquidus temperature of the second metallic material;   (vi) cooling the materials below the solidus temperature of the second metallic material so that a metallurgical bond is formed between the first and second metallic materials.   
     
     
         2 . A method of manufacturing a component as claimed in  claim 1 , including a further step of machining of the outside of the shell following cooling to remove any oxidation which occurs during the heating. 
     
     
         3 . A method of manufacturing a component as claimed in  claim 1 , whereby following heating of the metallic materials the temperature of the metallic materials is maintained above the liquidus temperature of the second metallic material for a sufficient period of time to allow at least partial fusion of the second material to the first material. 
     
     
         4 . A method of manufacturing a component as claimed in  claim 3 , wherein the temperature of the metallic materials is maintained above the liquidus temperature for at least 15 minutes. 
     
     
         5 . A method of manufacturing a component as claimed in  claim 1 , whereby the gas flow restricting means is a cover, the cover being sized and shaped to locate across the open end of the cavity. 
     
     
         6 . A method of manufacturing a component as claimed in  claim 1 , wherein the gas flow restricting means is a container within which some or all of the second metallic material is located. 
     
     
         7 . A method of manufacturing a component as claimed in  claim 6 , wherein the steps of providing the second metallic material and of providing the gas flow restricting means are achieved through providing the second metallic material in a container, the container having an opening complementary in shape to the open end of the cavity, and then inverting the container and locating it above the cavity. 
     
     
         8 . A method of manufacturing a component as claimed in  claim 1 , wherein the second metallic material is provided as alloy constituents, chosen so that when heated above their liquidus temperature the alloy constituents melt and mix to form a desired alloy composition, which bonds to the outer shell on cooling. 
     
     
         9 . A method of manufacturing a component as claimed in  claim 1 , wherein the first metallic material has a higher tensile strength than the second metallic material, and wherein the second metallic material is more resistant to abrasion than the first metallic material. 
     
     
         10 . A method of manufacturing a component as claimed in  claim 9 , wherein the first metallic material is a ferrous based material. 
     
     
         11 . A method of manufacturing a component as claimed in  claim 9 , wherein the first metallic material is a nickel or titanium based alloy. 
     
     
         12 . A method of manufacturing a component as claimed in  claim 9 , wherein the second metallic material is a white cast iron. 
     
     
         13 . A method of manufacturing a component as claimed in  claim 12 , wherein the second metallic material is a white cast iron containing carbides of at least one of chromium, molybdenum, tungsten, titanium, niobium, vanadium or boron.