Sintered body and production method thereof

Abstract

A sintered body is produced by preparing a metal powder mixture, compacting the metal powder mixture to provide a green compact and then sintering the green compact. The metal powder mixture includes a fine metal powder having a particle size of 75 μm or smaller, a graphite powder in an amount of 0.1 to 1.0% by mass and a powder lubricant in an amount of 0.05 to 0.80% by mass based on a total mass of the metal powder mixture.

What is claimed is:  
     
         1 . A sintered body, comprising: 
 sintered metal particles forming a sintered structure and having a maximum particle size of 100 μm or smaller; and    carbon being dispersed in the sintered structure in an amount of 0.05 to 1.0% by mass based on a total mass of the sintered body.    
     
     
         2 . A sintered body according to  claim 1 , wherein the sintered body has been heat-treated.  
     
     
         3 . A sintered body according to  claim 1 , wherein the sintered body forms at least teeth of a sprocket of a silent chain.  
     
     
         4 . A sintered body according to  claim 1 , wherein the sintered body is a high-strength part of an internal combustion engine.  
     
     
         5 . A sintered body having a sintered structure derived from a metal powder and containing carbon dispersed in the sintered structure in an amount of 0.05 to 1.0% by mass based on a total mass of the sintered body, the metal powder having a particle size of 75 μm or smaller.  
     
     
         6 . A sintered body according to  claim 5 , wherein the sintered body has been heat-treated.  
     
     
         7 . A sintered body according to  claim 5 , wherein the sintered body forms at least teeth of a sprocket of a silent chain.  
     
     
         8 . A sintered body according to  claim 5 , wherein the sintered body is a high-strength part of an internal combustion engine.  
     
     
         9 . A sintered body produced from a metal powder mixture, the metal powder mixture including a metal powder having a particle size of 75 μm or smaller, a graphite powder in an amount 0.1 to 1.0% by mass and a powder lubricant in an amount of 0.05 to 0.80% by mass based on a total mass of the metal powder mixture.  
     
     
         10 . A sintered body according to  claim 9 , wherein the sintered body has been heat-treated.  
     
     
         11 . A sintered body according to  claim 9 , wherein the sintered body forms at least teeth of a sprocket of a silent chain.  
     
     
         12 . A sintered body according to  claim 9 , wherein the sintered body is a high-strength part of an internal combustion engine.  
     
     
         13 . A production method of a sintered body, comprising: 
 preparing a metal powder mixture, the metal powder mixture including a fine metal powder having a particle size of 75 μm or smaller, a graphite powder in an amount of 0.1 to 1.0% by mass and a powder lubricant in an amount of 0.05 to 0.80% by mass based on a total mass of the metal powder mixture;    compacting the metal powder mixture to provide a green compact; and    sintering the green compact.    
     
     
         14 . A production method according to  claim 13 , wherein the sintered body comprises sintered metal particles forming a sintered structure and having a maximum particle size of 100 μm or smaller.  
     
     
         15 . A production method according to  claim 13 , wherein the sintered body contains carbon in an amount of 0.05 to 1.0% by mass based on a total mass of the sintered body.  
     
     
         16 . A production method according to  claim 13 , wherein the metal powder is a blend of an iron-based powder and an alloying metal powder.  
     
     
         17 . A production method according to  claim 13 , wherein said preparing includes granulating the metal powder to form primary particles having a particle size of 75 μm or smaller into secondary particles having a particle size of 180 μm or smaller.  
     
     
         18 . A production method according to  claim 13 , wherein the metal powder mixture is compacted while being heated to a temperature of 100° C. or higher.  
     
     
         19 . A production method according to  claim 18 , wherein said compacting includes preheating a die to a temperature of 120° C. or higher, and then, compressing the metal powder mixture into the preheated die.  
     
     
         20 . A production method according to  claim 13 , wherein said compacting includes applying a die lubricant to a die, and then, compressing the metal powder mixture into the die.  
     
     
         21 . A production method according to  claim 13 , wherein the green compact is sintered at a temperature of 1180° C. or higher.  
     
     
         22 . A production method according to  claim 13 , further comprising heat-treating the sintered compact.