# US 2014/0155249 A1 · Method for making amorphous particles using a uniform melt-state in a microwave generated plasma torch

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- Number: US 2014/0155249 A1
- Document ID: US20140155249A1
- Status: Published application
- Kind: A1
- Application number: 13/693,737
- Filed: 2012-12-04
- Published: 2014-06-05
- Earliest claimed: 2012-12-04
- Assignees: Amastan Technologies LLC
- Inventors: Kamal HADIDI; Makhlouf REDJDAL
- Web page: https://patentgrep.com/patent/US20140155249A1

## CPC

- C01B 21/0605: {Binary compounds of nitrogen with carbon}
- C01B 21/064: with boron
- C01B 21/0646: {Preparation by pyrolysis of boron and nitrogen containing compounds}
- C01B 21/0828: {Carbonitrides or oxycarbonitrides of metals, boron or silicon}
- C01B 32/991: Boron carbide
- C01F 5/06: by thermal decomposition of magnesium compounds (calcining magnesite or dolomite C04B2/10)
- C01F 7/162: Magnesium aluminates
- C01F 7/30: Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
- C01F 17/218: Yttrium oxides or hydroxides
- C01F 17/34: Aluminates, e.g. YAlO3 or Y3-xGdxAl5O12
- C04B 35/44: based on aluminates
- C04B 35/443: Magnesium aluminate spinel
- C04B 35/505: based on yttrium oxide
- C04B 35/563: based on boron carbide
- C04B 35/583: based on boron nitride
- C04B 35/622: Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B 35/62665: {Flame, plasma or melting treatment}
- H05H 1/30: using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/28 takes precedence)
- C01P 2002/02: Amorphous compounds
- C04B 2235/3206: Magnesium oxides or oxide-forming salts thereof
- C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
- C04B 2235/3222: Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
- C04B 2235/3225: Yttrium oxide or oxide-forming salts thereof
- C04B 2235/443: Nitrates or nitrites
- C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron
- C04B 2235/5481: Monomodal
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## 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

### Claim 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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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%.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

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).

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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

### Claim 9 (depends on 1)

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.

### Claim 10 (depends on 1)

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