COMPOSITE ARTICLE WITH MAGNETOCALORICALLY ACTIVE MATERIAL AND METHOD FOR ITS PRODUCTION

• US 20100116471A1
• Filed: 12/27/2007
• Published: 05/13/2010
• Est. Priority Date: 12/27/2007
• Status: Active Grant

• Current Assignee: Georg Werner Reppel, Matthias Katter
• Original Assignee: Vacuumschmelze GmbH & Company KG (Vectra Corp.)
• Inventors: Reppel, Georg Werner, Katter, Matthias
• Granted Patent: US 8,551,210 B2
• Time in Patent Office: Days
• US Class Current: 165/133
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B22F 3/12 Both compacting and sintering by forging B22F3/17
• CPC Class Codes: B29C 67/24 characterised by the choice of material
• CPC Class Codes: F25B 21/00 Machines, plants or systems, using electric or magnetic effects
• CPC Class Codes: F25B 2321/002 by using magneto-caloric effects
• CPC Class Codes: F28F 13/16 by applying an electrostatic field to the body of the heat-exchange medium
• CPC Class Codes: F28F 3/00 Plate-like or laminated elements; Assemblies of plate-like or laminated elements specially adapted for movement F28F5/00
• CPC Class Codes: H01F 1/012 adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material refrigeration systems using magnetic effects F25B21/00
• CPC Class Codes: H01F 1/015 Metals or alloys
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof

Abstract

A composite article (1; 10; 40) comprises a plurality of inclusions (5) of a magnetocalorically active material embedded in a matrix (4) of a magnetocalorically passive material. The inclusions (5) and the matrix (4) have a microstructure characteristic of a compacted powder.

Claims

1. A composite article, comprising:

(a) a solid matrix comprising a magnetocalorically passive material and having a microstructure comprising a plurality of particles of magnetocalorically passive material that have lattice structure that exhibits strain, or fractures, or both, from compression, and that, at least in part, touch one or more immediately neighboring particles of magnetocalorically passive material; and

(b) a plurality of solid inclusions comprising a magnetocalorically active material at least partially embedded in the solid matrix of a magnetocalorically passive material, wherein

the inclusions either;

(1) have a microstructure comprising a plurality of particles of magnetocalorically active material that have lattice structure that exhibits strain, or fractures, or both from compression, and that, at least in part, touch one or more immediately neighboring particles of magnetocalorically passive material, or

(2) form a series of foils flakes or tapes embedded in the matrix.

2. Composite article according to claim 1, wherein the microstructure of

the matrix comprises particles having an average particle size of less than 1000 μ

m.

3. Composite article according claim 1, wherein

the inclusions have an average diameter of less than 1000 μ

m.

4. Composite article according to claim 1, wherein

the inclusions further comprise a metallic corrosion protection coating.

5. Composite article according to claim 4, wherein

the metallic corrosion protection coating comprises one or more of Al, Cu, or Sn.

6. Composite article according to claim 1, wherein

the inclusions further comprise an outer coating of an electrically isolating material.

7. Composite article according to claim 1, wherein

the matrix further comprises an outer coating of

an electrically isolating material disposed on at least some of the particles of magnetocalorically passive material.

8. Composite article according to claim 6, wherein

the electrically isolating material comprises a polymer or a ceramic or an inorganic compound.

17. Composite article according to claim 1, wherein

the magnetocalorically active material has a Curie temperature T_c in the range 220K to 345K.

18. Composite article according to claim 1, wherein

the magnetocalorically active material is one or more of Gd, a La(Fe_1-bSi_b)₁₃-based phase, a Gd₅(Si, Ge)₄-based phase, a Mn(As, Sb)-based phase, a MnFe(P, As)-based phase, a Tb—

Gd-based phase, a (La, Ca, Pr, Nd, Sr)MnO₃-based phase, a Co—

Mn—

(Si, Ge)-based phase or a Pr₂(Fe, Co)₁₇-based phase.

19. Composite article according to claim 1, wherein

the matrix comprises one or more of the elements, Al, Cu, Ti, Mg, Zn, Sn, Bi and Pb.

20. Composite article according to claim 1, wherein

the matrix comprises one or more of BeO, AlN, BN, or graphite.

23. Composite article according to claim 1, wherein

the inclusions are present in a volume fraction of inclusions between 25% and 98%, of the volume of the composite article

24. Composite article according to claim 23, wherein

the volume fraction of inclusions is between 60% and 95%.

25. Composite article according to claim 1, wherein

the matrix comprises a soft magnetic material.

26. Composite article according to claim 25,

wherein

the soft magnetic material comprises one or more of Fe, FeSi, Co or Ni.

27. Composite article according to claim 1, wherein

the inclusions are disposed in a plurality of layers, each layer comprising inclusions of a magnetocalorically active material having a T_c which is different from the T_c of the magnetocalorically active material in an adjacent layer.

28. Composite article according to claim 1,

further comprising a surface having at least one channel therein.

29. Composite article according to claim 28, wherein

the at least one channel is adapted to direct the flow of a heat exchange medium in contact with the surface.

30. Composite article according to claim 1 further comprising an outer protective coating.

31. Composite article according to claim 30, wherein

the outer protective coating comprises a polymer or a metal or an alloy.

32. Composite article according to claim 1, wherein the composite article further comprises effective porosity.

33. Composite article according to claim 32, wherein

the effective porosity comprises at least one channel within the body of the composite article providing flow communication from a first side of the composite article to a second side of the composite article.

34. Composite article according to claim 32, wherein

the effective porosity comprises 10 vol. % to 60 vol. % of the composite article.

36. Heat exchanger comprising at least one composite article according to claim 1.

58. A refrigeration system comprising the heat exchanger according to claim 36.

59. An industrial, commercial, or domestic freezer comprising the refrigeration system according to claim 58.

60. A climate control device comprising the heat exchanger according to claim 36.

61. An air-conditioning unit comprising the climate control device according to claim 60.

9. A composite article, comprising:

(a) a solid matrix comprising a magnetocalorically passive material having a sintered microstructure comprising a plurality of grains of magnetocalorically passive material that have lattice structure that exhibits strain relief, and that, at least in part, touch one or more immediately neighboring grains of magnetocalorically passive material via an interface comprising interdiffused atoms from the neighboring grains, resulting from sintering a compressed powder of magnetocalorically passive material;

(b) a plurality of solid inclusions of comprising a magnetocalorically active material at least partially embedded in the solid matrix.

12. Composite article according to claim 9, wherein

the inclusions further comprise a metallic corrosion protection coating.

13. Composite article according to claim 12, wherein

the corrosion protection coating comprises one or more of Al, Cu, or Sn.

14. Composite article according to claim 9, wherein

the inclusions further comprise an outer coating of an electrically isolating material.

15. Composite article according to claim 9, wherein

the grains of the matrix further comprise an outer coating of an electrically isolating material.

16. Composite article according to claim 14, wherein

the electrically isolating material comprises a polymer a ceramic, or an inorganic compound.

21. Composite article according to claim 9, wherein

the matrix comprises grains having an average grain size of less than 1000 μ

m.

22. Composite article according to claim 9, wherein

the inclusions have an average diameter of less than 1000 μ

m.

56. Composite article according to claim 9, wherein the inclusions either:

(1) have a microstructure comprising a plurality of grains of magnetocalorically active material that have lattice structure that exhibits strain relief, and that, at least in part, touch one or more immediately neighboring grains of magnetocalorically active material via an interface comprising interdiffused atoms from the neighboring grains, resulting from sintering a compressed powder of magnetocalorically active material;

or

(2) form a series of foils, flakes, or tapes embedded in the matrix.

57. Composite article according to claim 56, wherein the inclusions have a microstructure comprising a plurality of grains of magnetocalorically active material that have lattice structure that exhibits strain relief, and that, at least in part, touch one or more immediately neighboring grains of magnetocalorically active material via an interface comprising interdiffused atoms from the neighboring grains, resulting from sintering a compressed powder of magnetocalorically active material.

10. (canceled)

11. (canceled)

35. (canceled)

37. A method of manufacturing a solid composite article, comprising:

providing a first powder comprising a magnetocalorically active material,

providing a second powder comprising a magnetocalorically passive material,

mixing the first powder and the second powder together to form a powder mixture, and

compacting the powder mixture to form a solid composite article comprising a solid matrix comprising the magnetocalorically passive material and a plurality of solid inclusions comprising a magnetocalorically active material at least partially embedded in the solid matrix.

38. Method according to claim 37, further comprising:

adding one or more of a lubricant, an organic binder or a dispersant to the powder mixture.

39. Method according to claim 37, wherein

the first powder comprises a plurality of particles which are have been coated with a metallic corrosion protection coating before mixing the first powder with the second powder.

40. Method according to claim 37, wherein

the first powder comprises a plurality of particles which have been coated with an electrically isolating material before mixing the first powder with the second powder (3).

41. Method according to claim 37, wherein

the second powder comprises a plurality of particles which have been coated with an electrically isolating material before mixing the second powder with the first powder.

42. Method according to claim 37, further comprising:

coating a plurality of particles of the first powder and a plurality of particles of the second powder with an electrically isolating material after mixing the first powder with the second powder.

43. Method according to claim 37, wherein the compacting is carried out

under a pressure of 10 MPa to 3000 MPa.

44. Method according to claim 37, wherein

the compacting comprises rolling or pressing.

45. Method according to claim 37, further comprising:

enveloping the powder mixture in a mantle before compaction.

46. Method according to claim 37, wherein

the compacting is carried out at room temperature or at a temperature between 30°

C. to 250°

C.

47. Method according to claim 37, further comprising:

heat treating the composite article after the compacting.

48. Method according to claim 47, wherein

the heat treating is carried out at a temperature between 300°

C. and 1200°

C. for a time between 2 hours and 10 hours.

49. Method according to claim 47, wherein

the heat treating is carried out under vacuum or in a protective atmosphere.

50. Method according to claim 37, further comprising:

compacting the composite article a second time.

51. Method according to claim 37, further comprising:

carrying out a finishing procedure.

52. Method according to claim 37, further comprising applying an outer protective coating to the composite article.

53. Method according to claim 52, wherein

the applying the outer protective coating comprises dipping, spraying, or electro-deposition.

54. Method according to claim 52 to claim 53, wherein the applying of

the outer protective coating occurs after a sintering heat treatment of the composite articles-carried-out.

55. Method according to claim 52, wherein the applying of

the outer protective coating occurs after compacting of composite article.