Method and apparatus for direct electrothermal-physical conversion of ceramic into nanopowder

• US 6,600,127 B1
• Filed: 09/13/2000
• Issued: 07/29/2003
• Est. Priority Date: 09/15/1999
• Status: Expired due to Fees

• Current Assignee: Novacentrix Corporation
• Original Assignee: Nano Gas Technologies, Inc.
• Inventors: Wilson, Dennis Eugene, Willauer, Darrin Lee, Peterson, Dennis Roger
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US09/661,330
• Time in Patent Office: 1,049 Days
• Field of Search: 219/121.47, 219/76.16, 219/121.36, 219/121.48, 219/121.52, 219/121.59, 219/121.43, 219/121.41, 427/255.1, 427/255.3, 427/255.2, 427/223, 427/249, 427/450, 427/576, 423/325, 423/345, 423/346, 423/440, 423/DIG.10, 75/101.9, 75/102.1
• US Class Current: 219/121.43
• 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 2219/0809 employing two or more electrodes
• CPC Class Codes: B01J 2219/0822 The electrode being consumed
• CPC Class Codes: B01J 2219/0826 essentially linear
• CPC Class Codes: B01J 2219/083 cylindrical
• CPC Class Codes: B01J 2219/0843 Ceramic
• CPC Class Codes: B01J 2219/0845 Details relating to the type of discharge
• CPC Class Codes: B01J 2219/0896 Cold plasma
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to 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: C01F 7/424 using a plasma
• CPC Class Codes: C01G 1/00 Methods of preparing compounds of metals not covered by subclasses C01B, C01C, C01D, or C01F, in general electrolytic production of inorganic compounds C25B1/00
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C04B 35/626 Preparing or treating the powders individually or as batches pigments for ceramics C09C1/0009; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
• CPC Class Codes: H05H 1/3425 Melting or consuming electrodes
• CPC Class Codes: H05H 1/3484 Convergent-divergent nozzles
• CPC Class Codes: Y10S 423/10 Plasma energized
• CPC Class Codes: Y10S 977/776 Ceramic powder or flake
• CPC Class Codes: Y10S 977/787 : Viscous fluid host/matrix containing nanomaterials
• CPC Class Codes: Y10S 977/889 : by laser ablation

Abstract

A process for synthesizing nanosized powders utilizes a hybrid exploding wire device containing a solid metal wire fuse in the bore of a tube that is open at each end. The ends of the fuse are connected to electrodes on the ends of the tube. The electrodes are designed to erode to maintain a heavy metal plasma. The bore may comprise a corresponding ceramic to be produced, and a microcrystalline powder of a corresponding ceramic may be retained within the bore. An electrical discharge vaporizes and ionizes the fuse. The tube confines the radial expansion of the plasma such that the plasma exits from both ends of the tube where it reacts with a suitable gas to form nanoscale particles. In addition, the plasma gas ablates and vaporizes a portion of the bore wall to contribute to the nanoceramic synthesis. Other alternatives include replacing the fuse with a thin conductive sheath or a consumable metal insert.

Claims

1. A system for producing powder, comprising:

a reactor vessel having an interior cavity with two open-ended exit ports;

an anode mounted adjacent to one of the exit ports;

a cathode mounted adjacent to the other of the exit ports; and

wherein

at least portions of the anode and the cathode are vaporized for generating powder via both exit ports.

2. The system of claim 1 wherein the interior cavity of the reactor vessel is a cylindrical bore and the exit ports are located at axial ends of the bore.

3. The system of claim 1 wherein the anode and the cathode are formed from the same material.

4. The system of claim 1, further comprising microparticles located within the interior cavity of the reactor vessel.

5. The system of claim 1, further comprising an automated loading mechanism for automatically reloading the reactor vessel.

6. A system for producing powder, comprising:

a reactor vessel having an interior cavity with two open-ended exit ports;

an anode mounted adjacent to one of the exit ports;

a cathode mounted adjacent to the other of the exit ports; and

production means for generating powder via both exit ports in response to a discharge.

7. The system of claim 6 wherein the production means includes ignition means associated with the reactor vessel for initiating the discharge therein.

8. The system of claim 6 wherein the interior cavity of the reactor vessel is a cylindrical bore and the exit ports are located at axial ends of the bore.

9. The system of claim 7 wherein the ignition means is a fuse extending between the anode, the cathode, and the production means.

10. The system of claim 6 wherein the anode and the cathode are formed from the same material.

11. The system of claim 6 wherein the production means vaporizes to force plasma out of both exit ports.

12. The system of claim 6, further comprising microparticles located within the interior cavity of the reactor vessel.

13. The system of claim 6 wherein the production means is a conductive insert.

14. The system of claim 7 wherein the production means is a conductive insert located approximately in a center of the interior cavity of the reactor vessel, and wherein the ignition means is a fuse.

15. The system of claim 6 wherein the production means is an encapsulated insert.

16. The system of claim 7 wherein the production means is an encapsulated insert located in approximately a center of the interior cavity of the reactor vessel, and wherein the ignition means is a fuse.

17. The system of claim 6 wherein the production means is an electrode located in the interior cavity of the reactor vessel.

18. The system of claim 6, further comprising an automated loading mechanism for automatically reloading the production means in the reactor vessel.

19. An electrothermal gun for producing nanoscale particles, comprising:

a reactor vessel having a cylindrical bore with two open ends and a reactor chamber at the ends containing a reactor gas;

an anode mounted to one of the ends of the bore;

a cathode mounted to the other of the ends of the bore;

ignition means associated with the reactor vessel for initiating a discharge therein; and

production means located within the bore of the reactor vessel for vaporizing in response to the discharge and forcing plasma to exit from both ends of the bore to generate nanoscale particles in the reactor chamber.

20. The electrothermal gun of claim 19 wherein the production means is a fuse sheath extending between the anode and cathode.

21. The electrothermal gun of claim 19 wherein the anode and the cathode are formed from the same material.

22. The electrothermal gun of claim 19, further comprising microparticles located within the bore of the reactor vessel.

23. The electrothermal gun of claim 19 wherein the production means is an insert located approximately in an axial center of the bore, and wherein the ignition means is a fuse.

24. The electrothermal gun of claim 23 wherein the insert is conductive.

25. The electrothermal gun of claim 23 wherein the insert is encapsulated.

26. The electrothermal gun of claim 23 wherein the insert is an electrode.

27. The electrothermal gun of claim 19, further comprising an automated loading mechanism for automatically reloading the production means in the reactor vessel.

28. A method of producing powder, comprising:

(a) providing a reactor vessel with a cavity having two open-ended exit ports, an anode, and a cathode;

(b) applying a voltage across the anode and cathode to initiate a discharge;

then

(c) vaporizing material in response to the discharge to form a plasma that exits both exit ports to generate powder.

29. The method of claim 28 wherein step (a) further comprises providing microparticles in the cavity, and wherein step (c) further comprises vaporizing and converting the microparticles into nanosized particles.

30. The method of claim 28 wherein step (c) comprises vaporizing and converting portions of the anode and the cathode into powder.

31. The method of claim 28 wherein step (c) comprises vaporizing a production material into powder.

32. The method of claim 28 wherein step (c) comprises ablating a conductive insert located approximately in a center of the cavity into powder.

33. The method of claim 28, further comprising the step of automatically reloading production material in the reactor vessel.