Mixed powder for iron-based powder metallurgy, method for producing same, and sintered body produced using same

Abstract

The mixed powder for iron-based powder metallurgy of the present invention comprises a powder containing calcium sulfate anhydrite II such that the CaS weight ratio after sintering is 0.01 wt % or more to 0.1 wt % or less. The powder containing calcium sulfate anhydrite II preferably has a volume-average particle size of 0.1 μm or more to 60 μm or less and preferably additionally contains one or more ternary oxides selected from the group consisting of Ca—Al—Si oxides and Ca—Mg—Si oxides. The weight ratio of the ternary oxides and CaS after the sintering is preferably 3:7 to 9:1.

1 . A mixed powder, comprising:
 an iron-containing powder; and   a powder comprising calcium sulfate anhydrite II, wherein weight ratio of CaS after sintering is 0.01 wt % or more to 0.1 wt % or less.   
     
     
         2 . The mixed powder according to  claim 1  wherein the powder comprising calcium sulfate anhydrite II has a volume-average particle size of 0.1 μm or more to 60 μm or less. 
     
     
         3 . The mixed powder according to  claim 1 , further comprising one or more ternary oxides selected from the group consisting of Ca—Al—Si oxides and Ca—Mg—Si oxides. 
     
     
         4 . The mixed powder according to  claim 3 , wherein a weight ratio of the ternary oxides and CaS after the sintering is 3:7 to 9:1. 
     
     
         5 . The mixed powder according to  claim 1 , wherein, when the powder comprising calcium sulfate anhydrite II has a volume-average particle size of R μm and the weight ratio of CaS contained in a sintered body after the sintering is W wt %, the following expression is satisfied:
 R 1/3 /W is 15 or more to 400 or less. 
 
     
     
         6 . The mixed powder according to  claim 1 , wherein the powder comprising calcium sulfate anhydrite II is covered with a lubricant or a binder. 
     
     
         7 . A sintered body prepared by sintering the mixed powder according to  claim 1 . 
     
     
         8 . A method for producing a mixed powder, comprising:
 preparing a powder comprising calcium sulfate anhydrite II by heating a powder comprising dihydrate gypsum or hemihydrate gypsum at a temperature of 300° C. or higher to 900° C. or lower; and   mixing the powder comprising calcium sulfate anhydrite II with an iron-containing powder.