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High temperature aerosol processing • • • • • • Overview Example of TiO2 Vapor phase generators Spray pyrolysis Spray generation Jung Hyeun Kim’s presentation Aerosol Reactors • Vapor Phase Reactors - Titania, Fumed Silica, Nitrides, etc. - Hot Wall, Flame, Plasma, Laser Ablation, Laser Pyrolysis • Spray Pyrolysis - Ferrites, Single and Multicomponent oxides, metals and alloys - Spray Nozzles - single and two fluid, Acoustic Sprayers and Nebulizers Problem Particles • Process Effluents - Power Plant Fly Ash, Smelter Emissions, Sintering Plants • Contaminants - Contamination in Pharmaceutical, Semiconductor Industries (Mr. Doug Kremer on Thursday) • Occupational Exposure Process Players • Solid/gas reactors - Reactant Feeding • Size Classification - Powder Dispersion in Gases • Coatings on Surfaces - Condensation PRODUCTS • Titania pigment, Carbon blacks, Fumed silica, Alumina etc. • Metals and alloys - Ni, Ag, Au, Pd electronics circuits • Multicomponent Oxides - Ferrites, Superconductors,Dielectrics • Nanoscale Materials Vapor Phase Reactors •Precursor is in vapor phase •Chemical reaction to condensable species or condensation of vapor happens to make products (can have combination of both) •Chemically reactive environment can be: flame, plasma, thermal with resistive heating, thermal via laser etc… •Condensation induced by mixing, expansion (big pressure gradients!) or both Titania Process Oxygen Agglomerates Flame Fuel Fabric Filter Molecular Clusters Thermophoresis Wall Deposits TiCl4 Product Titania Process • • • • Nucleation - Particle Formation Coagulation and Aggregate Formation Thermophoresis and Wall Losses Solid/Gas Separation - Fabric Filter(Bag House Collectors) Agglomeration and Aggregation Spray Pyrolysis •Very common method for making particles •Here precursor starts as droplets or solid particles •Thermal, plasma, flame also used as reaction environment but reaction is in liquid or solid phase (tiny microreactors!) •Mr. JH Kim will discuss this… Droplet Drying and Conversion •Drying and conversion rates affect morphology of the particles •Can have hollow particles or can shatter particles •Mr. Kim will talk about effect of solvent on chemistry of particles •How to make spray? Some examples… Video Images of Drying Droplet Time: 0 sec Time: 71 sec Time: 95 sec Time: 117 sec Time: 145 sec Time: 188 sec Condensation Aerosol Generator Gas Condenser Vaporizer Heater Nebulizer Aerosol Impaction Target Nebulizer/Condensation Generator Condenser Evaporator Nebulizer Aerosol
