Chromium metal powder

Patent metadata

Field	Value
Publication number	US-11117188-B2
Application number	US-201414915785-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	Sep 2, 2013
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

A metal powder has a chromium content of at least 90 Ma %, a nanohardness according to EN ISO 14577-1 of ≤4 GPa and/or a green strength measured according to ASTM B312-09 of at least 7 MPa at a compression pressure of 550 MPa.

First claim

The invention claimed is:

1. A metal powder, comprising:
a chromium content of at least 90 Ma %; and
a nanohardness HIT 0.005/5/1/5 according to EN ISO 14577-1 of ≤4 GPa.

2. The metal powder according to claim 1 , wherein the metal powder is chromium powder having a metallic purity ≥99.0 Ma %.

3. The metal powder according to claim 1 , wherein the metal powder is an alloyed powder or composite powder.

4. The metal powder according to claim 1 , wherein the metal powder is granulated.

5. The metal powder according to claim 1 , which further comprises a surface area according to BET of ≥0.05 m2/g with or without a surface-enlarging operation.

6. A method for producing a metal powder, the method comprising the following steps:
reducing at least one compound of the group consisting of chromium oxide and chromium hydroxide, optionally with an admixed solid carbon source, under at least temporary action of hydrogen and hydrocarbon to produce a metal powder having:
a chromium content of at least 90 Ma %; and
a nanohardness HIT 0.005/5/1/5 according to EN ISO 14577-1 of ≤4 GPa.

7. The method according to claim 6 , which further comprises:
heating the compound of the group consisting of chromium oxide and chromium hydroxide, optionally with an admixed solid carbon source, to a temperature TR with 1100° C.≤TR≤1550° C.;
optionally holding the temperature at 1100° C.≤TR≤1550° C.; and
at least temporarily setting the hydrocarbon partial pressure at 5 to 500 mbar at least during the heating step.

8. The method according to claim 6 , wherein the action of hydrogen and hydrocarbon occurs at least in a temperature range of 800 to 1050° C.

9. The method according to claim 8 , which further comprises setting the hydrocarbon partial pressure at 5 to 500 mbar at least in the temperature range of 800 to 1050° C.

10. The method according to claim 8 , which further comprises setting a sum of heating time and holding time in the temperature range of 800° C. to 1050° C. to be at least 45 minutes.

11. The method according to claim 6 , which further comprises setting a total pressure at 0.95 to 2 bar.

12. The method according to claim 6 , which further comprises reducing the compound of the group consisting of chromium oxide and chromium hydroxide under at least temporary action of a H 2 —CH 4 gas mixture.

13. The method according to claim 12 , which further comprises setting a H 2 /CH 4 volume ratio at 1 to 200 or 1.5 to 20.

14. The method according to claim 6 , which further comprises admixing a solid carbon source having at least one component selected from the group consisting of carbon black, activated carbon, graphite, carbon-releasing compound and mixtures thereof.

15. The method according to claim 14 , which further comprises using between 0.75 and 1.25 mol or between 0.90 and 1.05 mol of carbon per mol of oxygen in the chromium oxide or chromium hydroxide.

16. The method according to claim 6 , which further comprises at least partially reacting at least one compound selected from the group consisting of chromium oxide and chromium hydroxide under the action of hydrogen and hydrocarbon to form a chromium carbide selected from the group consisting of Cr 3 C 2 , Cr 7 C 3 and Cr 23 C 6 .

17. The method according to claim 16 , which further comprises at least partially reacting the chromium carbide with at least one compound selected from the group consisting of chromium oxide and chromium hydroxide to form chromium.

18. The method according to claim 6 , wherein the hydrocarbon is CH 4 .

Assignees

• Plansee Se

Inventors

• O'Sullivan Michael
• Sigl Lorenz

Classifications

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• B22F9/22 Primary

  using gaseous reductors · CPC title

• A61H33/065

  with steam generators · CPC title

• C22C37/06

  containing chromium · CPC title

• C22B34/32 Primary

  Obtaining chromium · CPC title