Sintered ferrous material contaning copper

Abstract

A process for the manufacture of a ferrous-based sintered article containing copper in the range from 12 to 26 weight % is described, the process including the steps of: making a powder mixture having a desired composition, at least a proportion of a total content of iron and copper being provided by an iron powder having copper indivisibly associated therewith for instance being pre-alloyed or diffusion bonded; compacting said powder mixture to form a green compact of an article to be produced and sintering said green compact.

1 . A process for the manufacture of a ferrous-based sintered article containing copper in the range from 12 to 26 weight %, the sintered article having a ferrous matrix comprising a martensitic structure, the process including the steps of: making a powder mixture having a desired composition, said powder mixture composition including at least some iron powder and, separately, martensite promoting material, at least a proportion of a total content of iron and copper being provided by an iron copper material selected from the group comprising: a diffusion bonded iron-copper powder and pre-alloyed iron-copper powder; compacting said powder mixture to form a green compact of an article to be produced and sintering said green compact to produce an article wherein the ferrous matrix has a martensitic structure.  
     
     
         2 . A process according to  claim 1  wherein the copper content lies in the range from 15 to 20 weight %.  
     
     
         3 . A process according either  claim 1  or  claim 2  wherein the powder mixture also contains a steel powder.  
     
     
         4 . A process according to  claim 3  wherein the steel powder contains chromium.  
     
     
         5 . A process according to  claim 3  wherein the steel powder contains molybdenum.  
     
     
         6 . A process according to  claim 3  wherein the steel powder contains nickel.  
     
     
         7 . A process according to  claim 3  wherein the steel powder is a high-speed steel powder.  
     
     
         8 . A process according to  claim 7  wherein the steel powder is an M3/2 steel powder.  
     
     
         9 . A process according to  claim 3  wherein the steel powder is a stainless steel powder.  
     
     
         10 . A process according to  claim 9  wherein the stainless steel powder is 316 steel.  
     
     
         11 . A process according to any one preceding claim wherein the powder mixture contains carbon powder.  
     
     
         12 . A process according to any one preceding claim wherein the iron-copper material has a composition in weight % of Fe-20 Cu.  
     
     
         13 . A process according to any one preceding claim wherein the powder mixture also includes elemental copper powder.  
     
     
         14 . A process according to any one preceding claim wherein the powder mixture includes an elemental powder which promotes the formation of martensite.  
     
     
         15 . A process according to  claim 14  wherein the element is selected from the group comprising: chromium, molybdenum and nickel.  
     
     
         16 . A process according to any one preceding claim further including the step of cryogenically treating the sintered material.  
     
     
         17 . A process according to any one preceding claim further including the step of tempering the sintered material.  
     
     
         18 . A process according to any one preceding claim further including the step of providing molybdenum disulphide or tungsten disulphide in the powder mixture.  
     
     
         19 . A sintered ferrous-based material article when made by the process of any one of preceding  claims 1  to  18 .  
     
     
         20 . A sintered article according to  claim 19 , the article comprising a valve seat insert for an internal combustion engine.