Chromium-containing powder or granulated powder

Patent metadata

Field	Value
Publication number	US-10464130-B2
Application number	US-201414914147-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	Sep 2, 2013
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

A powder or powder granulate includes a chromium content >80 Ma %, which contains 2 to 20 Ma % iron, optionally up to 5 Ma % dopant, and optionally up to 2 Ma % oxygen, wherein the chromium-containing particles at least partially have pores. The powder displays significantly improved compression behavior and allows the production of sintered components having a very homogeneous distribution of the alloy elements.

First claim

The invention claimed is:

1. A powder or powder granulate, comprising:
a chromium content >80 Ma %;
2 to 20 Ma % iron;
optionally up to 5 Ma % dopant;
optionally up to 2 Ma % oxygen;
iron-rich regions having an iron content >60 Ma %; and
chromium-rich regions having a chromium content >95 Ma % and forming chromium-containing particles at least partially having pores, said chromium-containing particles having a mean porosity determined by quantitative image analysis of >20 Vol %.

2. The powder or powder granulate according to claim 1 , wherein said chromium-containing particles are at least partially classified as porous according to the classification according to p. 472 of Vol. 7 of the ASM handbook of 2007.

3. The powder or powder granulate according to claim 1 , wherein said chromium-containing particles have a particle size d 50 >20 μm measured by laser diffractometry and a surface area >0.05 m 2 /g measured by BET.

4. The powder or powder granulate according to claim 1 , wherein said pores are at least regionally open-pored and cross-linked.

5. The powder or powder granulate according to claim 1 , which further comprises 0.005 to 5 Ma % of at least one dopant selected from the group consisting of scandium, yttrium, lanthanides, titanium, zirconium and hafnium.

6. The powder or powder granulate according to claim 1 , which further comprises 0.002 to 2 Ma % oxygen.

7. The powder or powder granulate according to claim 1 , wherein said iron-rich regions are at least partially provided as iron-containing particles.

8. The powder or powder granulate according to claim 1 , wherein said iron-rich regions are provided at least in one form selected from the group consisting of unbound/elementary iron and iron oxide.

9. The powder or powder granulate according to claim 1 , wherein said iron-rich regions are at least partially intercalated in said pores of said chromium-containing particles.

10. The powder or powder granulate according to claim 1 , wherein said iron-rich regions are connected to said chromium-containing particles at least partially by a diffusion connection.

11. The powder or powder granulate according to claim 1 , wherein said dopant is provided at least partially as an oxide in the form of particles.

12. The powder or powder granulate according to claim 1 , wherein said dopant is provided at least in one form selected from the group consisting of intercalated in said chromium-containing particles and deposited on a surface of said chromium-containing particles.

13. The powder or powder granulate according to claim 1 , wherein said chromium-rich regions have a nanohardness HIT 0.005/5/1/5 according to EN ISO 14577-1 of 4 GPa.

14. The powder or powder granulate according to claim 1 , which further comprises a particle size/granulate size d 50 of the powder or powder granulate measured by laser diffractometry of 10 μm<d 50 <800 μm.

15. A component, comprising:
a powder or powder granulate according to claim 1 .

16. A method for the powder-metallurgy production of a component, the method comprising the following steps:
providing a chromium content >80 Ma %;
providing 2 to 20 Ma % iron;
providing optionally up to 5 Ma % dopant;
providing optionally up to 2 Ma % oxygen;
providing iron-rich regions having an iron content >60 Ma %; and
providing chromium-rich regions having a chromium content >95 Ma % and forming chromium-containing particles at least partially having pores, the chromium-containing particles having a mean porosity determined by quantitative image analysis of >20 Vol %.

17. A method for producing a powder or powder granulate, the method comprising the following steps:
reducing at least one chromium-containing compound selected from the group consisting of oxides and hydroxides in at least partial chronological presence of a carbon source and hydrogen at 1100 to 1550° C. to produce a powder or powder granulate having:
a chromium content >80 Ma %;
2 to 20 Ma % iron;
optionally up to 5 Ma % dopant;
optionally up to 2 Ma % oxygen;
iron-rich regions having an iron content >60 Ma %; and
chromium-rich regions having a chromium content >95 Ma % and forming chromium-containing particles at least partially having pores, the chromium-containing particles having a mean porosity determined by quantitative image analysis of >20 Vol %.

18. The method according to claim 17 , which further comprises admixing the dopant to the chromium-containing compound before the reducing step.

19. The method according to claim 17 , which further comprises after the reducing step adding an iron-containing powder having an iron content >60 Ma %.

20. The method according to claim 19 , which further comprises annealing the powder or powder granulate at a temperature T with 400° C. <T<1200° C. after the step of adding the iron-containing powder.

21. The method according to claim 17 , which further comprises granulating the chromium-containing compound alone or optionally jointly with the dopant.

Assignees

• Plansee Se

Inventors

• O'Sullivan Michael
• Sigl Lorenz
• Hosp Thomas

Classifications

• B22F1/052

  characterised by a mixture of particles of different sizes or by the particle size distribution · CPC title

• B22F1/10

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

• B22F1/0655

  Hollow particles · CPC title

• B22F9/20

  starting from solid metal compounds · CPC title

• B22F2302/45

  Others, including non-metals · CPC title