Powdered metal component

Patent metadata

Field	Value
Publication number	US-10211465-B2
Application number	US-201414915957-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	Sep 2, 2013
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A powder metallurgical component has a chromium content of at least 80% by weight and pores and/or oxide inclusions which are present in the component. The number per unit area of a sum of pores and oxide inclusions at a cut surface through the component in at least one region is at least 10,000 per mm 2 .

First claim

The invention claimed is:

1. A powder metallurgical component, comprising:
a chromium content of at least 80% by weight;
at least one of pores or oxide inclusions present in the component;
said oxide inclusions having a chromium oxide content of at least 90 mol. %;
a sum of said pores and said oxide inclusions at a cut surface through the component in at least one region amounting to a number per unit area of at least 10,000 per mm 2 ; and
said region having an Al 2 O 3 content of <500 μg per 1 g of the component.

2. The powder metallurgical component according to claim 1 , wherein said number per unit area of said sum of said pores and said oxide inclusions at said cut surface is at least 90,000 per mm 2 .

3. The powder metallurgical component according to claim 1 , wherein said chromium content is at least 90% by weight.

4. The powder metallurgical component according to claim 1 , wherein said region of the component has a density over an entire component thickness of between 70% and 95% of a theoretical density.

5. The powder metallurgical component according to claim 1 , wherein at least 90% of said pores and at least 90% of said oxide inclusions each have a maximum equivalent diameter of not more than 12 μm.

6. The powder metallurgical component according to claim 1 , wherein at least 90% of said pores and at least 90% of said oxide inclusions each have an area of not more than 100 μm 2 .

7. The powder metallurgical component according to claim 1 , wherein said region has a total oxygen content of <20,000 μg per 1 g of the component.

8. The powder metallurgical component according to claim 1 , wherein said region has a total nitrogen content of <2000 μg per 1 g of the component.

9. The powder metallurgical component according to claim 1 , which further comprises an oxygen content increasing over a component thickness from a middle to edges of the component.

10. A process for producing a powder metallurgical component having a chromium content of at least 80% by weight, at least one of pores or oxide inclusions present in the component, and a sum of the pores and the oxide inclusions at a cut surface through the component in at least one region amounting to a number per unit area of at least 10,000 per mm 2 , the process comprising the following steps:
(i) providing a powder batch including chromium and optionally other metals, the chromium having a content of at least 80% by weight, based on a total metal content, and the powder batch including powder having a BET surface area of ≥0.05 m 2 /g;
(ii) pressing the powder batch to form a compact;
(iv) sintering the compact at from 1100 to 1500° C.;
(v) oxidizing the sintered component in a presence of an oxygen source; and
(vi) removing the oxide layer from the surface;
(vii) providing the oxide inclusions with a chromium oxide content of at least 90 mol. %; and
(viii) providing the region with an Al 2 O 3 content of <500 μg per 1 g of the component.

11. The process according to claim 10 , which further comprises (iii) presintering the compact at from 600 to 1000° C., between step (ii) pressing the powder batch to form a compact and step (iv) sintering the compact at from 1100 to 1500° C.

12. The process according to claim 10 , wherein the oxygen source is selected from the group consisting of H 2 O, O 2 , CO 2 and mixtures thereof.

13. The process according to claim 10 , which further comprises carrying out the sintering step under a hydrogen atmosphere.

14. The process according to claim 11 , which further comprises carrying out the presintering step under a hydrogen atmosphere.

15. The process according to claim 11 , which further comprises carrying out a calibration pressing operation between the presintering step and the sintering step.

16. The process according to claim 15 , which further comprises carrying out the calibration pressing operation at a specific pressing pressure of from 500 to 1000 MPa.

17. The process according to claim 10 , which further comprises, before pressing, adding a pressing aid to the powder batch in an amount of from 0.1% by weight to 5% by weight, based on an amount of the powder batch.

18. The process according to claim 10 , wherein the powder batch including chromium and optionally other metals includes at least 90% by weight chromium, based on a total metal content.

Assignees

• Plansee Se

Inventors

• O'Sullivan Michael
• Sigl Lorenz
• Brandner Marco
• Venskutonis Andreas
• Kraussler Wolfgang

Classifications

• H01M50/522

  Inorganic material · CPC title

• C22C1/1078

  by internal oxidation of material in solid state · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• B22F9/20

  starting from solid metal compounds · CPC title

• H01M8/0232 Primary

  Metals or alloys · CPC title