Method for making high purity and free flowing metal oxides powder
First Claim
1. A method of processing a metal oxide powder comprising the steps of:
- injecting a powder feed material into a plasma stream;
melting the powder feed material with said plasma stream to form molten droplets; and
cooling said molten droplets under free-fall conditions so as to form frozen spherical droplets such that said molten droplets have ample time for complete in-flight solidification before reaching a collection chamber,wherein said frozen spherical droplets have higher density and purity levels than the powder feed material.
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Abstract
According to aspects of the present invention, metal oxide powder, such as yttria and alumina powder (feed material), is processed using a plasma apparatus. The process generally consists of in-flight heating and melting of the feed material by the plasma apparatus. The plasma apparatus contains a plasma torch with required power supply and cooling systems, a powder feeder, a chamber to collect the powder and a dedusting system. The heated powder forms molten spherical droplets that are rapidly cooled under free fall conditions. The plasma densification process removes some impurity oxides, modifies the morphology of the particle and increases the apparent density of the powder.
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Citations
29 Claims
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1. A method of processing a metal oxide powder comprising the steps of:
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injecting a powder feed material into a plasma stream; melting the powder feed material with said plasma stream to form molten droplets; and cooling said molten droplets under free-fall conditions so as to form frozen spherical droplets such that said molten droplets have ample time for complete in-flight solidification before reaching a collection chamber, wherein said frozen spherical droplets have higher density and purity levels than the powder feed material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of processing a metal oxide powder comprising:
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injecting a powder feed material into a plasma stream; melting the powder feed material with said plasma stream to form molten droplets; and cooling said molten droplets under free-fall conditions so as to form frozen spherical droplets such that said molten droplets have ample time for complete in-flight solidification before reaching a collection chamber, wherein said frozen spherical droplets have higher density and purity levels than the powder feed material, and wherein the method forms a free-flowing powder having higher purity than the powder feed material. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of making a high-purity free-flowing powder comprising:
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injecting a powder feed material into a plasma stream; melting the powder feed material with said plasma stream to form molten droplets; and cooling said molten droplets under free-fall conditions so as to form frozen spherical droplets, wherein, during cooling, said molten droplets have ample time for complete in-flight solidification before reaching a collection chamber. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification