Mixed powder for powder metallurgy and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9868153-B2
Application number	US-201514615912-A
Country	US
Kind code	B2
Filing date	Feb 6, 2015
Priority date	Nov 9, 2010
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

This mixed powder for powder metallurgy, the powder having excellent fluidity and minimal graphite powder scattering, can be obtained relatively conveniently by mixing fine graphite having an average grain diameter of 4 μm or less with an iron based powder. The process is performed without the addition of a binder and while shearing force is applied. It is preferable that the fine graphite have an average grain diameter of 2.4 μm or less and be wet-milled. A portion of the fine graphite is preferably added in place of at least one constituent selected from the group consisting of carbon black, fullerene, carbon compounds carbonized by baking, and graphite having an average grain diameter of 5 μm or more.

First claim

The invention claimed is:

1. A method for manufacturing a mixed powder for powder metallurgy, comprising:
crushing graphite to a fine graphite with a mean particle size of 2.4 μm or less, and
mixing the fine graphite with an iron based powder while applying a shear force,
wherein the fine graphite is mixed with an iron based powder, without adding a binder,
the fine graphite is mixed with the iron based powder while applying the shear force using a mixer equipped with stirring vanes moving in such a manner as to cut the mixed powder of the fine graphite and the iron based powder, and
the mixed powder has a graphite scattering ratio of 20% or less.

2. The method according to claim 1 , wherein the mixed powder has a graphite scattering ratio of 15% or less.

3. The method according to claim 1 , wherein the mixed powder for powder metallurgy further comprises at least one selected from the group consisting of carbon black, fullerene, and a graphite with a mean particle size of 5 μm or more, mixed with the iron based powder.

4. The method according to claim 3 , wherein the ratio of the fine graphite to the total amount of the fine graphite, the graphite having a mean particle size of 5 μm or more, the carbon black, and the fullerene is 15% or more.

5. The method according to claim 4 , wherein the total amount of the fine graphite, the graphite having a mean particle size of 5 μm or more, the carbon black, and the fullerene is from 0.1 to 3 parts by mass per 100 parts by mass of the iron based powder.

6. The method according to claim 1 , wherein the mixed powder for powder metallurgy further comprises at least one component selected from the group consisting of a lubricant, a strength improver, an abrasion resistance improver, and a machinability improver.

7. The method according to claim 1 , wherein the mixed powder has a flowability of from 24.0 to 29.0 sec/50 g.

8. The method according to claim 1 , wherein the mixed powder has an apparent density of 3.08 to 3.25 g/cm 3 .

9. The method according to claim 1 , wherein the mixed powder has a flowability of from 24.0 to 29.0 sec/50 g and an apparent density of 3.08 to 3.25 g/cm 3 .

10. The method according to claim 1 , wherein the mixed powder has a graphite scattering ratio of 10% or less.

11. The method according to claim 1 , wherein the fine graphite with a mean particle size of 2.4 μm or less is prepared by crushing natural graphite.

12. A method for manufacturing a mixed powder for powder metallurgy, comprising:
crushing graphite to a fine graphite with a mean particle size of 2.4 μm or less, and
mixing the fine graphite with an iron based powder while applying a shear force,
wherein the fine graphite is mixed with an iron based powder to form a mixed powder, without adding a binder;
the fine graphite is mixed with the iron based powder while applying the shear force using a mixer equipped with stirring vanes moving in such a manner as to cut the mixed powder of the fine graphite and the iron based powder, and
the mixed powder has a graphite scattering ratio of 17% or less and a flowability of from 24.0 to 28.9 sec/50 g.

13. The method according to claim 12 , wherein the fine graphite has been subjected to wet crushing.

14. The method according to claim 13 , wherein the mixed powder for powder metallurgy further comprises at least one selected from the group consisting of carbon black, fullerene, and a graphite with a mean particle size of 5 μm or more, mixed with the iron based powder.

15. The method according to claim 13 , wherein the ratio of the fine graphite to the total amount of the fine graphite, the graphite having a mean particle size of 5 μm or more, the carbon black, and the fullerene is 15% or more.

16. The method according to claim 14 , wherein the total amount of the fine graphite, the graphite having a mean particle size of 5 μm or more, the carbon black, and the fullerene is from 0.1 to 3 parts by mass per 100 parts by mass of the iron based powder.

17. The method according to claim 12 , wherein the mixed powder for powder metallurgy further comprises at least one component selected from the group consisting of a lubricant, a strength improver, an abrasion resistance improver, and a machinability improver.

18. The method according to claim 12 , wherein the mixed powder has a graphite scattering ratio of 10% or less.

19. The method according to claim 12 , wherein the mixed powder has a graphite scattering ratio of 15% or less.

Assignees

• Kobe Steel Ltd

Inventors

• Suzuki Hironori

Classifications

• B22F1/105 Primary

  containing inorganic lubricating or binding agents, e.g. metal salts · CPC title

• B22F1/12

  Metallic powder containing non-metallic particles (containing lubricating or binding agents or organic material B22F1/10) · CPC title

• B22F1/14

  Treatment of metallic powder (mixing with lubricating or binding agents or with organic material B22F1/10) · CPC title

• B22F1/10 Primary

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• C22C2026/001

  Fullerenes · CPC title