METHOD FOR THE DENSIFICATION AND SPHEROIDIZATION OF SOLID AND SOLUTION PRECURSOR DROPLETS OF MATERIALS USING MICROWAVE GENERATED PLASMA PROCESSING

• US 20140131906A1
• Filed: 11/13/2012
• Published: 05/15/2014
• Est. Priority Date: 11/13/2012
• Status: Active Grant

• Current Assignee: 6K Incorporated
• Original Assignee: Amastan Technologies LLC
• Inventors: Hadidi, Kamal, Redjdal, Makhlouf
• Granted Patent: US 9,023,259 B2
• Time in Patent Office: Days
• US Class Current: 264/5
• 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:

a) introducing feed material through a materials feeder into a microwave plasma torch;

b) entraining said feed material using laminar flow towards a microwave generated plasma;

c) processing said feed material by exposing it to a uniform temperature profile within the microwave generated plasma;

d) quenching plasma exhaust of said microwave generated plasma;

e) filtering the exhaust gas of said microwave generated plasma; and

f) extracting powder products from said filtered 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 axissymmetric microwave plasma torch and said feed material is introduced along the central axis of said axissymmetric 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 at quenching rates not less than 10³°

C./sec.

9. The method of claim 1 wherein the filtering step includes filtering the exhaust from the microwave plasma through bag filters and collecting spherical powder.

10. The method of claim 1 wherein the filtering step includes quenching into water.

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