8/28/10
SPRAY SYNTHESIS OF NANOMATERIALS
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In the Plasma Based Ultrafine Particle Synthesis Process (PSP), a liquid precursor is atomized and injected into the high temperature plasma flame. The atomized droplet enters the high temperature flame where the solvent evaporates, precursor materials condense, chemical reactions initiate and nucleation and growth of the grains mat then occur; followed by formation of dense active particles and accelerated towards the collecting surface. To collect particles either as a deposit on a substrate an Electrostatic Precipitator (ESP) is used to collect the synthesized nanopowders. Other methods use stagnation point surfaces to collect powders. A plate electrostatic precipitator, consisting of a pair of polished stainless steel plates separated by a few mm thick ceramic insulator and applied with electric field is placed parallel to the trajectory of the spray beam to collect spray particles by electrophoresis.
The yield and characteristics of the synthesized nanomaterials depend strongly on the properties of the precursors, geometry of the atomizer and spray process variables such as the size and velocity distribution of the aerosol droplets, flame characteristics and flame-droplet interactions.
Spray synthesis of nanomaterials requires fundamental understanding and control of the aerosol, its injection into the high pressure high temperature plasma and plasma-droplet interactions. It has been observed that aqueous solutions produce wider distributions of large droplets which form particles with large grains while metalorganic solutions produce a narrow range of fine grained material. Increasing the precursor concentration and feed rate increases the powder collection rate.
The yield and characteristics of the synthesized nanomaterials depend strongly on the properties of the precursors, geometry of the atomizer and spray process variables such as the size and velocity distribution of the aerosol droplets, flame characteristics and flame-droplet interactions.
Spray synthesis of nanomaterials requires fundamental understanding and control of the aerosol, its injection into the high pressure high temperature plasma and plasma-droplet interactions. It has been observed that aqueous solutions produce wider distributions of large droplets which form particles with large grains while metalorganic solutions produce a narrow range of fine grained material. Increasing the precursor concentration and feed rate increases the powder collection rate.
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