Method for the densification and spheroidization of solid and solution precursor droplets of materials using microwave generated plasma processing

• US 9,259,785 B2
• Filed: 04/30/2015
• Issued: 02/16/2016
• Est. Priority Date: 11/13/2012
• Status: Active Grant

• Current Assignee: 6K Incorporated
• Original Assignee: Amastan Technologies LLC
• Inventors: Hadidi, Kamal, Redjdal, Makhlouf
• Primary Examiner(s): THEISEN, MARY LYNN F
• Application Number:
  US14/700,847
• Publication Number:
  US 20150231701A1
• Time in Patent Office: 292 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B22F 2009/0836 with electric or magnetic field or induction
• CPC Class Codes: B22F 2009/0872 by water
• CPC Class Codes: B22F 9/026 Spray drying of solutions or suspensions
• CPC Class Codes: B22F 9/082 atomising using a fluid using centrifugal force B22F9/10
• CPC Class Codes: B29B 9/10 by moulding the material, i.e. treating it in the molten state
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: H05H 1/30 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence

Abstract

A method for processing feed material to produce dense and spheroidal products is described. The feed material is comprised of powder particles from the spray-drying technique or solution precursor droplets from ceramic or metallic materials. The feed material is processed using plasma generated from a microwave. The microwave plasma torch employed is capable of generating laminar flow during processing which allows for the production of spheroidal particles with a homogenous materials distribution. This results in products having improved thermal properties, improved corrosion and wear resistance and a higher tolerance to interface stresses.

Claims

1. A method of producing spheroidal and dense powder products which comprises:

introducing feed material through a materials feeder into a microwave plasma torch, wherein the feed material includes ceramic or metallic materials;

entraining said feed material using an axis-symmetric laminar entrainment flow towards a microwave generated plasma;

guiding said feed material towards the microwave generated plasma using an axis-symmetric laminar cooling flow;

processing said feed material within the microwave generated plasma;

quenching a plasma exhaust gas of said microwave generated plasma; and

extracting powder products from the quenched plasma exhaust gas.

2. The method of claim 1 wherein said feed material is a powder with a substantially non-spherical shape.

3. The method of claim 1 wherein said feed material is a homogenous solution or a suspension of solution precursors injected as droplets.

4. The method of claim 1 wherein the microwave plasma torch is an axis-symmetric microwave plasma torch and said feed material is introduced along the central axis of said axis-symmetric microwave plasma torch.

5. The method of claim 1 wherein said materials feeder uses a fluidized bed.

6. The method of claim 1 wherein the materials feeder is a nebulizing atomizer which produces a mist of droplets having a diameter size ranging between 0.5 micrometers and 200 micrometers.

7. The method of claim 1 wherein the materials feeder is a droplet maker which uses a piezo electric transducer that injects uniform droplets to obtain uniformly dense and spherical products.

8. The method of claim 1 wherein the quenching step includes cooling the microwave plasma exhaust gas at quenching rates not less than 10³°

C./sec.

9. The method of claim 1 further comprising filtering the quenched plasma exhaust gas from the microwave plasma through bag filters and collecting spherical powder.

10. The method of claim 9 wherein filtering the quenched plasma exhaust gas includes quenching into water.

11. The method of claim 1 wherein the powder products are densified to a range of 95% to 100%.