Production of nanoparticles and microparticles

• US 7,883,606 B2
• Filed: 09/09/2004
• Issued: 02/08/2011
• Est. Priority Date: 09/10/2003
• Status: Expired due to Fees

• Current Assignee: Nahum Parkansky, Raymond Leon Boxman
• Original Assignee: Nahum Parkansky, Raymond Leon Boxman
• Inventors: Parkansky, Nahum, Boxman, Raymond Leon
• Primary Examiner(s): Mayekar; Kishor
• Application Number:
  US10/571,569
• Publication Number:
  US 20070080054A1
• Time in Patent Office: 2,343 Days
• Field of Search: 204/178
• US Class Current: 204/178
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 2219/0813 employing four electrodes
• CPC Class Codes: B01J 2219/0839 Carbon
• CPC Class Codes: B01J 2219/0841 Metal
• CPC Class Codes: B01J 2219/0849 Corona pulse discharge
• CPC Class Codes: B01J 2219/0867 Six or more (electro)magnets
• CPC Class Codes: B01J 2219/0877 Liquid
• CPC Class Codes: B01J 2219/0894 Processes carried out in the presence of a plasma
• CPC Class Codes: B01J 8/005 Separating solid material from the gas/liquid stream separation processes per se B01D
• CPC Class Codes: B22F 1/07 Metallic powder characterised by particles having a nanoscale microstructure nanosized particles B22F1/054
• CPC Class Codes: B22F 2202/01 Use of vibrations
• CPC Class Codes: B22F 2202/13 Use of plasma
• CPC Class Codes: B22F 2207/07 Particles with core-rim gradient
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 9/14 using electric discharge
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 32/05 Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
• CPC Class Codes: H05H 1/48 using an arc H05H1/26 takes precedence

Abstract

A method of producing microparticles including: (a) providing a system including: (i) a vessel containing a liquid; (ii) at least a first pair of electrodes; (iii) a mechanism for igniting an electrical arc between the electrodes; (b) disposing the first pair of electrodes within the liquid, and (c) effecting at least one pulsed electrical discharge between the electrodes so as to produce a plasma bubble, and to produce the microparticles, the microparticles being associated with the plasma bubble, wherein the pulsed electrical discharge has a pulse duration of less than 1000 microseconds, and wherein the pulsed electrical discharge has a current amplitude of at least 1 ampere (A).

Claims

1. A method of producing microparticles comprising the steps of:

(a) providing a system including;

(i) a vessel containing a liquid;

(ii) at least a first pair of electrodes;

(iii) a mechanism for igniting an electrical arc between said electrodes;

(b) disposing said first pair of electrodes within said liquid, and

(c) effecting at least one pulsed electrical discharge between said electrodes so as to produce a plasma bubble, and to produce the microparticles, the microparticles being associated with said plasma bubble,

wherein said pulsed electrical discharge has a pulse duration of less than 1000 microseconds, and wherein said pulsed electrical discharge has a current amplitude of at least 1 ampere (A).

2. The method of claim 1, wherein said pulse duration is less than 100 microseconds.

3. The method of claim 1, wherein said pulse duration is less than 50 microseconds.

4. The method of claim 3, wherein said pulsed electrical discharge has a current amplitude of at least 10 A.

5. The method of claim 3, wherein said pulsed electrical discharge has a current amplitude of at least 10 A and less than 100 A.

6. The method of claim 1, wherein said pulse duration is less than 30 microseconds.

7. The method of claim 1, wherein said pulse duration is less than 10 microseconds.

8. The method of claim 1, wherein said pulse duration is less than 3 microseconds.

9. The method of claim 1, wherein said pulse duration is less than 1 microsecond.

10. The method of claim 1, wherein said pulsed electrical discharge is repeatedly applied.

11. The method of claim 1, wherein said pulsed electrical discharge is repeatedly applied at a frequency in a range of 10 Hertz to 1 MHertz.

12. The method of claim 1, wherein said electrical discharge is ignited by drawing an arc.

13. The method of claim 12, wherein said pulsed electrical discharge between said electrodes is a plurality of pulsed electrical discharges, said discharges being effected by a periodical contacting of a first electrode of said first pair of electrodes with a second electrode of said first pair of electrodes.

14. The method of claim 13, wherein one of said first pair of electrodes is mounted on a vibrating mechanism which effects said periodical contacting between said first pair of electrodes.

15. The method of claim 1, wherein the microparticles have a particle size distribution (PSD), the method further comprising the step of:

(d) controlling a function of a product (P) of said current amplitude and said pulse duration, so as to control said PSD of the microparticles.

16. The method of claim 1, wherein the microparticles have a particle size distribution (PSD), and wherein said PSD is shifted towards more particles of smaller sizes by decreasing a product (P) of said current amplitude and said pulse duration, the method further comprising the step of:

(d) controlling P so as to control said PSD of the microparticles.

17. The method of claim 16, wherein P is controlled such that said PSD has a median particle size below 100 nanometers.

18. The method of claim 16, wherein P is controlled such that said PSD has a median particle size below 20 nanometers.

19. The method of claim 1, wherein said effecting of said pulsed electrical discharge is controlled such that said liquid contributes atoms to the microparticles.

20. The method of claim 1, wherein said liquid includes an alcohol.

21. The method of claim 1, wherein said liquid includes kerosene.

22. The method of claim 1, wherein said liquid contains atoms of sulfur.

23. The method of claim 1, wherein said liquid contains atoms of at least one of the elements selected from the group consisting of molybdenum, tungsten, and sulfur.

24. The method of claim 1, wherein at least one of said first pair of electrodes is a metal.

25. The method of claim 1, wherein at least one of said first pair of electrodes contains a material selected from the group consisting of iron, nickel, tungsten, and carbon.

26. The method of claim 1, wherein at least one of said first pair of electrodes is fabricated from graphite.

27. The method of claim 1, wherein at least one of said first pair of electrodes is fabricated from silicon.

28. The method of claim 1, wherein said effecting of said pulsed electrical discharge is controlled so as to collapse said plasma bubble.

29. The method of claim 1, further comprising the step of:

(d) removing the microparticles produced by said electrical discharge.

30. The method of claim 29, wherein said removing of the microparticles is effected by evaporation of said liquid.

31. The method of claim 29, wherein said removing of the microparticles is effected by sedimentation.

32. The method of claim 29, further comprising the step of:

(d) effecting a classification of the microparticles produced by said electrical discharge.

33. The method of claim 32, wherein said classification includes classification based on a relative particle size of the microparticles.

34. The method of claim 32, wherein said classification includes classification based on a magnetic property of at least a portion of the microparticles.

35. The method of claim 32, wherein said classification includes classification based on an electrical property of at least a portion of the microparticles.

36. The method of claim 29, wherein the microparticles have an electrical charge when disposed in said liquid, and wherein said removing is effected by:

(i) placing at least one collector electrode into said liquid;

(ii) imposing a bias voltage upon said collector electrode;

(iii) allowing the microparticles to be attracted to said collector electrode having said bias voltage, and

(iv) removing said collector electrode from said liquid.

37. The method of claim 29, wherein the microparticles have a magnetic charge, and wherein said removing is effected by:

(i) placing a magnet in the liquid;

(ii) allowing the microparticles to be attracted to said magnet, and

(iii) removing said magnet from said liquid.

38. The method of claim 29, wherein said removing of the microparticles is effected by at least one collector placed in said liquid, and said liquid is caused to flow from said electrodes to said collector.

39. The method of claim 38, wherein said liquid, after flowing to said collector, is re-circulated to a vicinity of said electrodes.

40. The method of claim 38, wherein said liquid is added to said vessel in controlled amounts.

41. The method of claim 29, wherein said removing of the microparticles is effected by at least two collector electrodes, said collector electrodes being disposed at different depths within said liquid.

42. The method of claim 29, wherein said removing of the microparticles is effected by removing a portion of said liquid from a specified height from a bottom of said vessel.

43. The method of claim 42, wherein said height is within an upper 10% of a height of said liquid within said vessel.