Integrated thermal process for the continuous synthesis of nanoscale powders
First Claim
1. A process for producing a nanoscale powder from a precursor material comprising the following steps:
- evaporating the precursor material in a gaseous atmosphere in a thermal reactor so as to create a vapor/gas mixture with a temperature of at least 3000K;
initiating nucleation of the precursor material from the vapor/gas mixture prior to quenching in a zone adjacent to the thermal reactor; and
quenching said vapor/gas mixture by effecting its expansion through a predetermined pressure drop, thereby causing the formation of nanoscale particles of product material in a product gas.
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Abstract
A continuous process that produces nanoscale powders from different types of precursor material by evaporating the material and quenching the vaporized phase in a converging-diverging expansion nozzle. The precursor material suspended in a carrier gas is continuously vaporized in a thermal reaction chamber under conditions that favor nucleation of the resulting vapor. Immediately after the initial nucleation stages, the vapor stream is rapidly and uniformly quenched at rates of at least 1,000 K/sec, preferably above 1,000,000 K/sec, to block the continued growth of the nucleated particles and produce a nanosize powder suspension of narrow particle-size distribution. The nanopowder is then harvested by filtration from the quenched vapor stream and the carrier medium is purified, compressed and recycled for mixing with new precursor material in the feed stream.
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Citations
25 Claims
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1. A process for producing a nanoscale powder from a precursor material comprising the following steps:
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evaporating the precursor material in a gaseous atmosphere in a thermal reactor so as to create a vapor/gas mixture with a temperature of at least 3000K; initiating nucleation of the precursor material from the vapor/gas mixture prior to quenching in a zone adjacent to the thermal reactor; and quenching said vapor/gas mixture by effecting its expansion through a predetermined pressure drop, thereby causing the formation of nanoscale particles of product material in a product gas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A process for producing a nanoscale powder from a precursor material comprising the following steps:
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reacting the precursor material with a reactive component in a thermal reactor so as to create a vapor/gas mixture with a temperature of at least 3000K; initiating nucleation of the precursor material from the vapor/gas mixture prior to quenching in a zone adjacent to the thermal reactor and; quenching said vapor/gas mixture by effecting its expansion through a predetermined pressure drop, thereby causing formation of nanoscale particles of a product material in a product gas. - View Dependent Claims (22, 23, 24, 25)
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Specification