METHOD FOR MAKING AMORPHOUS PARTICLES USING A UNIFORM MELT-STATE IN A MICROWAVE GENERATED PLASMA TORCH

• US 20140155249A1
• Filed: 12/04/2012
• Published: 06/05/2014
• Est. Priority Date: 12/04/2012
• Status: Active Grant

• Current Assignee: 6K Incorporated
• Original Assignee: Kamal Hadidi, Makhlouf Redjdal
• Inventors: HADIDI, Kamal, REDJDAL, Makhlouf
• Granted Patent: US 8,951,496 B2
• Time in Patent Office: Days
• US Class Current: 501/152
• CPC Class Codes: C01B 21/0605 Binary compounds of nitrogen with carbon
• CPC Class Codes: C01B 21/064 with boron
• CPC Class Codes: C01B 21/0646 Preparation by pyrolysis of boron and nitrogen containing compounds
• CPC Class Codes: C01B 21/0828 Carbonitrides or oxycarbonitrides of metals, boron or silicon
• CPC Class Codes: C01B 32/991 Boron carbide
• CPC Class Codes: C01F 17/218 Yttrium oxides or hydroxides
• CPC Class Codes: C01F 17/34 Aluminates, e.g. YAlO3 or Y3-xGdxAl5O12
• CPC Class Codes: C01F 5/06 by thermal decomposition of magnesium compounds calcining magnesite or dolomite C04B2/10
• CPC Class Codes: C01F 7/162 Magnesium aluminates
• CPC Class Codes: C01F 7/30 Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
• CPC Class Codes: C01P 2002/02 Amorphous compounds
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/443 Nitrates or nitrites
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5481 Monomodal
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/443 Magnesium aluminate spinel
• CPC Class Codes: C04B 35/505 : based on yttrium oxide
• CPC Class Codes: C04B 35/563 : based on boron carbide
• CPC Class Codes: C04B 35/583 : based on boron nitride
• CPC Class Codes: C04B 35/622 : Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
• CPC Class Codes: C04B 35/62665 : Flame, plasma or melting treatment
• CPC Class Codes: H05H 1/30 : using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence

Abstract

Feed material comprising uniform solution precursor droplets is processed in a uniform melt state using microwave generated plasma. The plasma torch employed is capable of generating laminar gas flows and providing a uniform temperature profile within the plasma. Plasma exhaust products are quenched at high rates to yield amorphous products. Products of this process include spherical, highly porous and amorphous oxide ceramic particles such as magnesia-yttria (MgO—Y₂O₃). The present invention can also be used to produce amorphous non oxide ceramic particles comprised of Boron, Carbon, and Nitrogen which can be subsequently consolidated into super hard materials.

Claims

1. A method of producing amorphous powder particles using a uniform melt state process comprising:

a) introducing axially uniform precursor droplets from a feed injection device 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 high temperature profile within said microwave generated plasma;

d) quenching at a high rate the plasma exhaust of said microwave generated plasma;

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

f) extracting amorphous powder particle products from said filtered exhaust gas.

2. The method of claim 1 wherein the feed material is comprised of homogenous precursor solutions of nitrates, acetates, alkoxides, or organometallics.

3. The method of claim 1 wherein the axially introduced uniform precursor droplets have a diameter between 1 and 300 micrometers and a size distribution not exceeding 5%.

4. The method of claim 1 wherein the axially introduced precursor droplets are not uniform and have diameters less than 100 microns and are produced by a gas atomization process.

5. The method of claim 1 wherein the plasma torch is axisymmetric.

6. The method of claim 1 wherein the quenching step is done in air, or under inert gas conditions, and the quenching rates are less than or equal to 10⁶ degrees Kelvin per second (K/s).

7. The method of claim 1 wherein the amorphous powder products are collected using ceramic or stainless steel filters with pore diameters not exceeding the diameter of the product particles.

8. The method of claim 1 wherein the product particles are spherical, dense or porous, and uniform in diameter.

9. The method of claim 1 wherein the powder particles are compound oxides such as MgO, Y₂O₃, Al₂O₃, or oxide composites, such as magnesia-yttria (MgO—

Y₂O₃), yttria-alumina, and magnesia-alumina, or other metal oxides.

10. The method of claim 1 wherein the powder product particles are non-oxide compounds with the chemical formula C₃N₄, BN, BC₄, or BC₂N.