METHOD AND APPARATUS FOR NANOPOWDER AND MICROPOWDER PRODUCTION USING AXIAL INJECTION PLASMA SPRAY

• US 20100176524A1
• Filed: 03/29/2007
• Published: 07/15/2010
• Est. Priority Date: 03/29/2006
• Status: Abandoned Application

• Current Assignee: Northwest Mettech Corporation
• Original Assignee: Northwest Mettech Corporation
• Inventors: Bogdanovic, Nikica, Burgess, Alan W.
• Application Number:
  US12/294,976
• Publication Number:
  US 20100176524A1
• Time in Patent Office: Days
• US Class Current: 264/12
• CPC Class Codes: B01F 33/404 for mixing material moving continuously therethrough, e.g. using impinging jets
• CPC Class Codes: B01J 2/04 in a gaseous medium if combined with suspending the material in a gas, e.g. fluidised beds B01J2/16
• CPC Class Codes: B22F 1/05 Metallic powder characterised by the size or surface area of the particles
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 2202/01 Use of vibrations
• CPC Class Codes: B22F 2202/03 Treatment under cryogenic or supercritical conditions
• CPC Class Codes: B22F 2202/06 Use of electric fields
• CPC Class Codes: B22F 2202/13 Use of plasma
• 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 9/06 starting from liquid material
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C23C 4/123 Spraying molten metal
• CPC Class Codes: H05H 1/42 with provisions for introducing materials into the plasma, e.g. powder, liquid arc stabilising or constricting arrangements H05H1/3405; coaxial protecting fluids H05H1/341; electrostatic spraying, spraying apparatus with means for charging the spray electrically B05B5/00 ; cf. B23K9/324, B05B7/22

Abstract

A method and system for production of powders, such as micropowders and nanopowders, utilizing an axial injection plasma torch. Liquid precursor is atomized and injected into the convergence area of the plasma torch. The hot stream of particles is subsequently quenched and the resultant powders collected.

Claims

1. Method of manufacturing nanopowders or micropowders, comprising:

i) providing an axially injected plasma torch comprising a convergence chamber;

ii) axially delivering a liquid precursor to said plasma torch;

iii) atomizing said liquid precursor prior to delivery to said convergence chamber thereby forming a hot stream of particles in the plasma stream generated by said torch;

iv) introducing said hot stream of particles into a chamber;

v) introducing a quenching gas or liquid into said chamber at a quenching location;

vi) cooling said hot stream of particles and collecting the powder thereby produced.

2. The method of claim 1 wherein said quenching gas or liquid is introduced into said chamber at an angle to the radius of said chamber to thereby form a cyclonic flow.

3. The method of claim 2 wherein said quenching gas or liquid is also introduced as a curtain along the walls of said chamber.

4. The method of claim 1 wherein the particle temperature cooling rate of said particles in said stream is modified by providing a heat shroud between said torch and said quenching location.

5. The method of claim 1 wherein said quenching gas or liquid is introduced into said chamber through a quenching ring and the particle temperature cooling rate of said particles in said stream is modified by adding or subtracting additional quenching rings.

6. The method of claim 1 wherein the particle temperature cooling rate of said particles in said stream before quenching is modified by modifying the distance between the torch and the quenching location.

7. The method of claim 1 wherein the residence time of said particles in said stream is modified by providing a heat shroud between said torch and said quenching location.

8. The method of claim 1 wherein the residence time of said particles in said stream before quenching is modified by modifying the distance between the torch and the quenching location.

9. The method of claim 1 wherein the size of said particles in said stream is modified by modifying the torch parameters selected from the group consisting of gas composition, gas flow and power level.

10. The method of claim 1 wherein the size of said particles in said stream is modified by modifying the atomizing parameters selected from the group consisting of liquid feed rate and atomizing gas flow rate.

11. The method of claim 1 wherein the size of said particles in said stream is modified by modifying the velocity, volume, angle of incidence of and composition of said quenching gas.

12. The method of claim 1 wherein said cooling of said hot stream of particles after introduction of said quenching gas is carried out by adding a stream of cooling gas to said hot stream during transport.

13. The method of claim 1 wherein said quenching gas or liquid is selected from the group consisting of air, argon, nitrogen, carbon dioxide or water.

14. A system for manufacturing nanopowders or micropowders comprising:

i) feed means for delivering a liquid precursor;

ii) an axially injected plasma spray torch comprising a convergence chamber;

iii) atomizing means for atomizing said liquid precursor prior to delivery to said convergence chamber thereby forming a hot stream of particles in the plasma stream generated by said torch;

iv) a chamber for reaction of said hot stream of particles with a quenching gas;

v) means for introducing said quenching gas to said chamber at a quenching location; and

vi) means for collecting the nanopowders or micropowders thereby produced.

15. The system of claim 14 wherein said chamber comprises a variable number of chamber sections.

16. The system of claim 14 wherein said means for introducing said quenching gas to said chamber comprises a variable number of gas-introducing flanges.

17. The system of claim 14 further comprising a hot shroud between said torch and said quenching location.

18. The system of claim 17 wherein said hot shroud comprises:

i) an inner cylinder of a high melting point metal;

ii) an outer cylinder; and

iii) a flow of water provided in the space between said inner and outer cylinders.

19. The system of claim 17 wherein said hot shroud comprises:

i) an inner cylinder of a ceramic or graphite;

ii) an outer cylinder; and

iii) a flow of an inert gas provided in the space between said inner and outer cylinders.

20. The system of claim 18 wherein said inner cylinder is made from a material selected from the group consisting of tungsten, molybdenum and stainless steel.

21. The system of claim 19 wherein said inner cylinder is made from a material selected from the group consisting of graphite, zirconia, yttria stabilized zirconia, alumina zirconia, and calcia stabilized zirconia.