Methods for making a sintered body

Abstract

A method for making a sintered body, which comprises: providing a mixed powder which includes a first coarse metal powder and a second coarse metal powder, the first coarse metal powder is a matrix powder, the second coarse metal powder is a granulate of a fine primary powder, a weight percentage of the second coarse metal powder in the mixed powder is between 5% and 50%, and the second coarse metal powder has a substantially spherical powder morphology with a median particle size less than 100 μm; placing the mixed powder into a mold and applying a forming pressure to the mixed powder to form a green body; and sintering the green body at a temperature higher than 1,100° C. to form a high-density sintered body.

What is claimed is: 
     
         1 . A method for making a sintered body, comprising:
 providing a mixed powder which includes a first coarse metal powder and a second coarse metal powder, wherein the first coarse metal powder is a matrix powder, the second coarse metal powder is a granulate of a fine primary powder, a weight percentage of the second coarse metal powder in the mixed powder is between 5% and 50%, and the second coarse metal powder has a substantially spherical powder morphology with a median particle size less than 100 μm;   placing the mixed powder into a mold and applying a forming pressure to the mixed powder to form a green body; and   sintering the green body at a temperature higher than 1,100° C. to form a high-density sintered body.   
     
     
         2 . The method of  claim 1 , wherein the fine primary powder in the second coarse metal powder is an elemental powder, a pre-alloyed powder, an intermetallic compound powder, a carbide powder, a composite powder, a master alloy powder or a combination thereof, and a median particle size of the fine primary powder is less than 15 μm. 
     
     
         3 . The method of  claim 1 , wherein the second coarse metal powder is a spray dried spherical powder. 
     
     
         4 . The method of  claim 1 , wherein the median particle size of the second coarse metal powder is equal to or less than 45 μm. 
     
     
         5 . The method of  claim 1 , wherein the first coarse metal powder is an elemental powder, admixed powder, diffusion-bonded powder, pre-alloyed powder, binder-bonded powder, composite powder or a combination thereof, and a median particle size of the first coarse metal powder is between 50 μm and 110 μm. 
     
     
         6 . The method of  claim 1 , wherein the first coarse metal powder is an Fe-based powder and contains at least one alloying element, and a total weight of the alloying element accounts for less than 10% by weight of the first coarse metal powder, the alloying element includes at least one of the following:
 less than 8% by weight of nickel;   less than 2% by weight of molybdenum;   less than 1.5% by weight of manganese;   less than 4% by weight of chromium;   less than 3% by weight of copper;   less than 1.5% by weight of cobalt;   less than 1.5% by weight of tungsten;   less than 1.5% by weight of silicon;   less than 1% by weight of niobium; and   less than 1% by weight of vanadium.   
     
     
         7 . The method of  claim 1 , wherein the first coarse metal powder is an Fe-based powder and contains 0.5% to 2.5% by weight of nickel, 0.2% to 1.5% by weight of molybdenum, 0.01% to 1.0% by weight of manganese and unavoidable impurities. 
     
     
         8 . The method of  claim 1 , wherein the first coarse metal powder is an Fe-based powder and contains 0.5% to 4.5% by weight of nickel, 0.2% to 1.5% by weight of molybdenum, 0.5% to 2% by weight of copper, 0.01% to 1.0% by weight of manganese and unavoidable impurities. 
     
     
         9 . The method of  claim 1 , wherein the second coarse metal powder is an Fe-based powder and contains 8% to 20% by weight of chromium, 5% to 20% by weight of nickel, less than 5% by weight of molybdenum, less than 2% by weight of manganese, less than 5% by weight of copper, less than 1.5% by weight of silicon, less than 2% by weight of niobium and unavoidable impurities. 
     
     
         10 . A method for making a sintered body, comprising:
 providing a granulated powder with a substantially spherical powder morphology, wherein the granulated powder comprises a first metal powder and a second metal powder with a finer particle size than the first metal powder, wherein a median particle size of the first metal powder is between 50 μm and 110 μm, a median particle size of the second metal powder is less than 15 μm, and a weight percentage of the second metal powder in the granulated powder is between 5% between 50%;   placing the granulated powder into a mold and applying a forming pressure to the granulated powder to form a green body; and   sintering the green body at a temperature higher than 1,100° C. to form a high-density sintered body.   
     
     
         11 . The method of  claim 10 , wherein the first metal powder is an elemental powder, an admixed powder, a diffusion-bonded powder, a pre-alloyed powder, a binder-bonded powder, a composite powder or a combination thereof. 
     
     
         12 . The method of  claim 10 , wherein the second metal powder is an elemental powder, a pre-alloyed powder, an intermetallic compound powder, a carbide powder, a composite powder, a master alloy powder or a combination thereof. 
     
     
         13 . The method of  claim 10 , wherein the first metal powder is an Fe-based powder and contains at least one alloying element, and a total weight of the alloying element accounts for less than 10% by weight of the first metal powder, the alloying element includes at least one of the following:
 less than 8% by weight of nickel;   less than 2% by weight of molybdenum;   less than 1.5% by weight of manganese;   less than 4% by weight of chromium;   less than 3% by weight of copper;   less than 1.5% by weight of cobalt;   less than 1.5% by weight of tungsten;   less than 1.5% by weight of silicon;   less than 1% by weight of niobium; and   less than 1% by weight of vanadium.   
     
     
         14 . The method of  claim 10 , wherein the first metal powder is an Fe-based powder and contains 0.5% to 2.5% by weight of nickel, 0.2% to 1.5% by weight of molybdenum, 0.01% to 1.0% by weight of manganese and unavoidable impurities. 
     
     
         15 . The method of  claim 10 , wherein the first metal powder is an Fe-based powder and contains 0.5% to 4.5% by weight of nickel, 0.2% to 1.5% by weight of molybdenum, 0.5% to 2% by weight of copper, 0.01% to 1.0% by weight of manganese and unavoidable impurities. 
     
     
         16 . The method of  claim 10 , wherein the second metal powder is an Fe-based powder and contains 8% to 20% by weight of chromium, 5% to 20% by weight of nickel, less than 5% by weight of molybdenum, less than 2% by weight of manganese, less than 5% by weight of copper, less than 1.5% by weight of silicon, less than 2% by weight of niobium and unavoidable impurities.