Nanocomposite ceramic and method for producing the same

• US 20070259768A1
• Filed: 11/09/2006
• Published: 11/08/2007
• Est. Priority Date: 05/03/2006
• Status: Abandoned Application

• Current Assignee: Rutgers University
• Original Assignee: Rutgers University
• Inventors: Kear, Bernard H., McEnerney, Bryan W., Sadangi, Rajendra K., Niesz, Dale E.
• Application Number:
  US11/595,086
• Publication Number:
  US 20070259768A1
• Time in Patent Office: Days
• US Class Current: 501/120
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 35/117 Composites
• CPC Class Codes: C04B 35/443 Magnesium aluminate spinel
• CPC Class Codes: C04B 35/62665 Flame, plasma or melting treatment
• CPC Class Codes: C04B 35/6455 Hot isostatic pressing

Abstract

A nanocomposite ceramic includes a uniform combination of a ceramic spinel phase and an alumina phase, wherein each phase exhibits a grain size in the range of from about 0.1 nm to 10,000 nm.

Claims

1. A nanocomposite ceramic comprising a uniform combination of at least two hard ceramic phases, wherein each phase exhibits an average grain size of less than 10,000 nm.

2. The nanocomposite ceramic of claim 1, wherein the at least two hard ceramic phases comprises a ceramic spinel phase and an alumina phase.

3. The nanocomposite ceramic of claim 1, wherein the average grain size is from about 0.1 nm to 10,000 nm.

4. The nanocomposite ceramic of claim 1, wherein the average grain size is less than 100 nm.

5. The nanocomposite ceramic of claim 4, wherein the average grain size is from about 0.1 nm to 100 nm.

6. The nanocomposite ceramic of claim 2, wherein the alumina phase is α

-alumina.

7. The nanocomposite ceramic of claim 2, wherein the ceramic spinel phase has a general formula of (X²⁺)(Al³⁺)₂(O²⁻

)₄, with X representing a divalent cation.

8. The nanocomposite ceramic of claim 7, wherein X is selected from the group consisting of magnesium, zinc, iron, and manganese.

9. The nanocomposite ceramic of claim 2, wherein the ceramic spinel phase is an aluminate.

10. The nanocomposite ceramic of claim 9, wherein the aluminate is magnesium aluminum oxide.

11. The nanocomposite ceramic of claim 2, wherein the combination comprises a volume fraction ratio of alumina:

spinel in the range of from about 60-40;

40-60.

12. The nanocomposite ceramic of claim 2, wherein the combination comprises a bicontinuous structure, wherein the ceramic spinel phase and the alumina phase are interwoven in three dimensions.

13. The nanocomposite ceramic of claim 2, wherein the combination comprises a volume fraction ratio of alumina:

spinel in the range of from about 90-60;

10-40 and from about 10-40;

90-60.

14. The nanocomposite ceramic of claim 1, wherein the combination comprises a particle-dispersed structure wherein the minor fraction is a dispersed phase and the major fraction is a matrix phase.

15. A method for fabricating a nanocomposite ceramic of claim 1, comprising:

transforming a ceramic feed material comprising at least two hard ceramic phases into a metastable crystalline phase having an amorphous, short-range order structure; and

sintering the metastable crystalline phase under elevated pressures and temperatures for a sufficient time to yield the nanocomposite ceramic.

16. The method ceramic of claim 15, wherein the at least two hard ceramic phases comprises a ceramic spinel phase and an alumina phase.

17. The method of claim 15, wherein the metastable crystalline phase is in a form selected from the group consisting of a powder, a coating, a deposit and a preform.

18. The method of claim 15, wherein the ceramic feed material is in the form selected from the group consisting of a powder and an aerosol of a precursor solution.

19. The method of claim 18, wherein the ceramic feed material comprises particles having an average particle size of from about 0.1 micrometer to 200 micrometer.

20. The method of claim 19, wherein the average particle size is from about 0.1 micrometer to 50 micrometer.

21. The method of claim 19, wherein the average particle size is from about 5 micrometer to 100 micrometer.

22. The method of claim 19, wherein the average particle size is from about 10 micrometer to 200 micrometer.

23. The method of claim 18, wherein the ceramic feed material is in the form of a powder.

24. The method of claim 23, wherein the transforming step comprises:

melting the ceramic feed material to yield molten particles; and

quenching the molten particles rapidly to yield the metastable crystalline material.

25. The method of claim 24, prior to the transforming step, further comprising:

spray drying the ceramic feed material; and

heat treating the ceramic feed material at a sufficient temperature and for a sufficient time to remove organic impurities therefrom, and enhance structural strength to the particles of the ceramic feed material.

26. The method of claim 24, wherein the melting step comprises injecting the ceramic feed material into a high enthalpy plasma flame.

27. The method of claim 26, wherein the ceramic feed material is injected axially into the high enthalpy plasma flame.

28. The method of claim 26, wherein the ceramic feed material is injected radially into the high enthalpy plasma flame.

29. The method of claim 26, further comprising enclosing the high enthalpy plasma flame in a tubular heat resistant, refractory shroud.

30. The method of claim 24, wherein the quenching step comprises depositing the molten particles into a cold water bath.

31. The method of claim 24, wherein the quenching step comprises depositing the molten particles onto a cold substrate.

32. The method of claim 24, wherein the quenching step comprises delivering the molten particles through a supersonic nozzle.

33. The method of claim 18, wherein the ceramic feed material is in the form of an aerosol of a precursor solution.

34. The method of claim 33, wherein the transforming step comprises:

vaporizing the ceramic feed material to yield vaporized particles; and

condensing the vaporized particles rapidly to yield the metastable intermediate material.

35. The method of claim 34, wherein the vaporizing step comprises injecting the ceramic feed material into a high enthalpy plasma flame.

36. The method of claim 35, wherein the ceramic feed material is injected axially into the high enthalpy plasma flame.

37. The method of claim 35, wherein the ceramic feed material is injected radially into the high enthalpy plasma flame.

38. The method of claim 35, further comprising enclosing the high enthalpy plasma flame in a tubular heat resistant, refractory shroud.

39. The method of claim 34, wherein the condensing step comprises quenching the vaporized particles into a cold water bath.

40. The method of claim 34, wherein the condensing step comprises quenching the vaporized particles on a cold substrate.

41. The method of claim 34, wherein the condensing step comprises delivering the vaporized particles through a supersonic nozzle.

42. The method of claim 15, wherein the ceramic feed material comprises a mixture of alumina and the spinel.

43. The method of claim 15, wherein the ceramic feed material comprises an aluminum containing phase and a magnesium containing phase.

44. The method of claim 43, wherein the aluminum containing phase comprises aluminum trihydrate.

45. The method of claim 43, wherein the magnesium containing phase is magnesium carbonate.

46. The method of claim 15, wherein the ceramic feed material comprises an oxide.

47. The method of claim 46, wherein the oxide is selected from the group consisting of magnesium oxide, zinc oxide, iron oxide, and manganese oxide.

48. The method of claim 47, wherein the oxide is magnesium oxide.

49. The method of claim 15, wherein the pressure-assisted sintering is in the range of from about 0.1 to 5 GPa.

50. The method of claim 49, wherein the pressure-assisted sintering is in the range of from about 0.1 to 3 GPa.

51. The method of claim 15, wherein the pressure-assisted sintering temperature is in the range of from about 25% to 60% of the melting point of the metastable intermediate material.

52. The method of claim 15, wherein the pressure-assisted sintering time is in the range of from about 15 minutes to 14 hours.

53. The method of claim 15, wherein the sintering time is in the range of from about 15 minutes to 8 hours.