Sintered material, gear, and method for producing sintered material

Abstract

A sintered material with a composition composed of an iron-based alloy and a structure in which the number of compound particles 0.3 μm or more in size is less than 200 per 100 μm×100 μm unit area in a cross section, wherein the sintered material has a relative density of 93% or more.

1 . A sintered material comprising:
 a composition composed of an iron-based alloy; and   a structure in which the number of compound particles 0.3 μm or more in size is less than 200 per 100 μm×100 μm unit area in a cross section,   wherein the sintered material has a relative density of 93% or more.   
     
     
         2 . The sintered material according to  claim 1 , wherein the relative density is 97% or more. 
     
     
         3 . The sintered material according to  claim 1 , wherein a ratio of n 20  to n, (n 20 /n)×100, is 1% or less, wherein n denotes the number of the compound particles 0.3 μm or more in size per the unit area, and n 20  denotes the number of compound particles 20 μm or more in size per the unit area. 
     
     
         4 . The sintered material according to  claim 1 , wherein the iron-based alloy contains at least one element selected from the group consisting of C, Ni, Mo, Mn, Cr, B, and Si, a remainder being Fe and impurities. 
     
     
         5 . A gear comprising the sintered material according to  claim 1 . 
     
     
         6 . A method for producing a sintered material, comprising the steps of:
 preparing a raw powder containing an iron-based powder;   forming a green compact with a relative density of 93% or more from the raw powder; and   sintering the green compact,   wherein the iron-based powder contains at least one of a pure iron powder and an iron-based alloy powder,   the iron-based powder is subjected to reduction treatment in the step of preparing the raw powder, and   the iron-based powder is heated in a reducing atmosphere to a temperature of 950° C. or more and less than 1100° C. in the reduction treatment.   
     
     
         7 . The method for producing a sintered material according to  claim 6 , wherein the temperature is maintained for 5 hours or more in the reduction treatment. 
     
     
         8 . The sintered material according to  claim 2 , wherein a ratio of n 20  to n, (n 20 /n)×100, is 1% or less, wherein n denotes the number of the compound particles 0.3 μm or more in size per the unit area, and n 20  denotes the number of compound particles 20 μm or more in size per the unit area. 
     
     
         9 . The sintered material according to  claim 2 , wherein the iron-based alloy contains at least one element selected from the group consisting of C, Ni, Mo, Mn, Cr, B, and Si, a remainder being Fe and impurities. 
     
     
         10 . The sintered material according to  claim 3 , wherein the iron-based alloy contains at least one element selected from the group consisting of C, Ni, Mo, Mn, Cr, B, and Si, a remainder being Fe and impurities. 
     
     
         11 . The sintered material according to  claim 8 , wherein the iron-based alloy contains at least one element selected from the group consisting of C, Ni, Mo, Mn, Cr, B, and Si, a remainder being Fe and impurities. 
     
     
         12 . A gear comprising the sintered material according to  claim 2 . 
     
     
         13 . A gear comprising the sintered material according to  claim 3 . 
     
     
         14 . A gear comprising the sintered material according to  claim 4 . 
     
     
         15 . A gear comprising the sintered material according to  claim 8 . 
     
     
         16 . A gear comprising the sintered material according to  claim 9 . 
     
     
         17 . A gear comprising the sintered material according to  claim 10 . 
     
     
         18 . A gear comprising the sintered material according to  claim 11 .