Method of fabricating an article for magnetic heat exchanger

1. A method of fabricating an article for magnetic heat exchange, comprising:

plastically deforming a composite body comprising a binder having a glass transition temperature TG and a powder comprising a magnetocalorically active phase or elements in amounts suitable to produce a magnetocalorically active phase such that at least one dimension of the composite body changes in length by at least 10%, wherein the binder comprises a polypropylene carbonate, and the magnetocalorically active phase comprises La 1-a R a (Fe 1-x-y T y M x ) 13 H z C b wherein M is Si and, optionally, Al, T is one or more of the elements from the group consisting of Mn, Co, Ni, Ti, V and Cr and R is one or more of the elements from the group consisting of Ce, Nd, Y and Pr, wherein 0≤a≤0.5, 0.05≤x≤0.2, 0.003≤y≤0.2, 0≤z≤3 and 0≤b≤1.5.

2. The method according to claim 1 , wherein the composite body is plastically deformed such that an elongated form is produced having a first dimension that is at least 1.5 times greater than a second dimension.

3. The method according to claim 1 , wherein the composite body is plastically deformed such that an ellipsoid form is produced having a long axis that is at least 1.5 times greater than a shortest axis.

4. The method according to claim 1 , wherein the plastically deforming the composite body comprises plastically deforming the composite body at a temperature T which is above the glass transition temperature TG of the binder.

5. The method according to claim 4 , wherein T>TG+20K.

6. The method according to claim 1 , wherein the plastically deforming the composite body comprises plastically deforming the composite body by rolling.

7. The method according to claim 6 , wherein the rolling comprises passing the composite body between two rolls rotating in opposing directions.

8. The method according to claim 6 , wherein the rolling comprises passing the composite body between two rolls rotating with differing speeds.

9. The method according to claim 1 , wherein the plastically deforming the composite body comprises pressing a roller against a band, the surfaces of the roller and the band moving at substantially the same speed.

10. The method according to claim 1 , wherein the plastically deforming the composite body comprises pressing a roller against a band, the surfaces of the roller and the band moving at differing speeds.

11. The method according to claim 1 , wherein the composite body has a substantially cylindrical shape and the plastically deforming the composite body comprises treating the composite body in a spheronizer.

12. The method according to claim 1 , wherein the plastically deforming the composite body comprises plastically deforming the composite body in an inert atmosphere.

13. The method according to claim 1 , wherein the composite body comprises 0.1 weight percent to 10 weight percent binder.

14. The method according to claim 13 , wherein the composite body comprises 0.5 weight percent to 4 weight percent binder.

15. The method according to claim 1 , wherein the binder has a decomposition temperature of less than 300° C.

16. The method according to claim 15 , wherein the binder has a decomposition temperature of less than 200° C.

17. The method according to claim 1 , further comprising removing the binder from the composite body to form a green body, sintering the green body and producing an article for magnetic heat exchange.

18. The method according to claim 17 , wherein the removing the binder is carried out at a temperature of less than 400° C.

19. The method according to claim 17 , wherein the removing the binder is carried out in at least one of the group consisting of a noble gas, a hydrogen-containing atmosphere and a vacuum.

20. The method according to claim 17 , wherein the removing the binder is carried out for 30 minutes to 20 hours.

21. The method according to claim 17 , wherein at least 90% by weight of the binder is removed.

22. The method according to claim 21 , wherein more than 95% by weight of the binder is removed.

23. The method according to claim 17 , wherein the sintering is carried out at a temperature between 900° C. and 1200° C.

24. The method according to claim 23 , wherein the sintering is carried out at a temperature between 1050° C. and 1150° C.

25. The method according to claim 17 , wherein the sintering is carried out in a noble gas, a hydrogen containing atmosphere or a vacuum.

26. The method according to claim 17 , wherein the green body for a total sintering time trot, wherein the green body is sintere in vacuum for 0.95t tot to 0.75t tot and subsequently in a noble gas or hydrogen-containing atmosphere for 0.05t tot to 0.25t tot .

27. The method according to claim 20 , wherein the removing the binder is carried out for 2 hours to 6 hours.