Article for magnetic heat exchange and method of fabricating an article for magnetic heat exchange

Patent metadata

Field	Value
Publication number	US-9773591-B2
Application number	US-200913059352-A
Country	US
Kind code	B2
Filing date	May 6, 2009
Priority date	May 6, 2009
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

An article for magnetic heat exchange comprising a magnetocalorically active phase with a NaZn 13 -type crystal structure is provided by hydrogenating a bulk precursor article. The bulk precursor article is heated from a temperature of less than 50° C. to at least 300° C. in an inert atmosphere and hydrogen gas only introduced when a temperature of at least 300° C. is reached. The bulk precursor article is maintained in a hydrogen containing atmosphere at a temperature in the range 300° C. to 700° C. for a selected duration of time, and then cooled to a temperature of less than 50° C.

First claim

The invention claimed is:

1. A method of fabricating an article for magnetic heat exchange, comprising:
providing a bulk precursor article comprising a magnetocalorically active phase with a NaZn 13 crystal structure,
performing hydrogenation of the bulk precursor article by:
heating the bulk precursor article from a temperature of less than 50° C. to at least 300° C. in an inert atmosphere,
introducing hydrogen gas only when a temperature of at least 300° C. is reached,
maintaining the bulk precursor article in a hydrogen containing atmosphere at a temperature in the range 300° C. to 700° C. for a selected duration of time, and
cooling the bulk precursor article to a temperature of less than 50° C. to provide a hydrogenated article.

2. The method according to claim 1 , wherein the cooling of the bulk precursor article to a temperature of less than 50° C. is in a hydrogen-containing atmosphere.

3. The method according to claim 2 , wherein the selected duration of time is 1 minute to 4 hours.

4. The method according to claim 2 , wherein after the hydrogenation, the article comprises at least 0.21 wt % hydrogen.

5. The method according to claim 2 , wherein after the hydrogenation, the article comprises a magnetic phase transition temperature of in the range of −40° C. to +150° C.

6. The method according to claim 2 , wherein the bulk precursor article is cooled at a rate of 0.1K/min to 10K/min.

7. The method according to claim 1 , further comprising, before cooling the bulk precursor article to a temperature of less than 50° C., replacing the hydrogen gas by inert gas.

8. The method according to claim 7 , wherein the selected duration of time is 1 minute to 4 hours.

9. The method according to claim 7 , wherein after the hydrogenation, the article comprises a hydrogen content in the range of 0.02 wt % to 0.21 wt %.

10. The method according to claim 7 , wherein the cooling of the bulk precursor article is cooled at a rate of 1 K/min to 100 K/min.

11. The method according to claim 1 , wherein the cooling of the bulk precursor article to a temperature of less than 50° C. comprises cooling the bulk precursor article to a temperature in the range 300° C. to 150° C. in a hydrogen containing atmosphere, replacing the hydrogen by inert gas, and cooling the bulk precursor article to a temperature of less than 50° C.

12. The method according to claim 1 , wherein the bulk precursor article has initial outer dimensions before hydrogenation and the article after hydrogenation has final outer dimensions, wherein a difference between the initial outer dimensions and final outer dimensions is less than 10 volume %.

13. The method according to claim 1 , wherein the introducing of hydrogen gas is only when a temperature of 400° C. to 600° C. is reached.

14. The method according to claim 1 , wherein the bulk precursor article has at least one outer dimension greater than 5 mm.

15. The method according to claim 1 , wherein the bulk precursor article is polycrystalline.

16. The method according to claim 1 , wherein the bulk precursor article is sintered or reactive sintered.

17. The method according to claim 1 , wherein the magnetocalorically active phase is La 1-a R a (Fe 1-x-y T y M x ) 13 H z , wherein M is at least one element from the group consisting of Si and Al, T is at least one element from the group consisting of Co, Ni, Mn and Cr, R is at least one element from the group consisting of Ce, Nd and Pr, 0≦a≦0.5, 0.05≦x≦0.2, 0≦y≦0.2 and 0≦z≦3.

Assignees

• Katter Matthias
• Zellmann Volker
• Vacuumschmelze Gmbh & Co Kg

Inventors

• Katter Matthias
• Zellmann Volker

Classifications

• C22C33/0278

  with at least one alloying element having a minimum content above 5% · CPC title

• C22C38/02

  containing silicon · CPC title

• H01F1/015 Primary

  Metals or alloys · CPC title

• C22C2202/02

  Magnetic · CPC title

• C22C38/04

  containing manganese · CPC title