High-Rate Production of High-Purity, Nonagglomerated Oxide Nanopowders in Flames

High rate (∼50 g/hr) synthesis of nanoparticles of oxides such as SiO₂, TiO₂ and Al₂O₃ has been demonstrated in a reduced pressure flat flame reactor. The new process, called Combustion Flame - Chemical Vapor Condensation (CF-CVC), is a modification of the original CVC process which involves pyrolysis of chemical precursors in the gas phase. Careful selection of flow parameters has resulted in powders which are only loosely agglomerated, significantly enhancing their usefulness in commercial applications. The nanopowders have a narrow particle size distribution with a mean particle size controllable between 5 and 50 nm. The powder characteristics, post treatments and commercial applications of these powders will be discussed. Furthermore, chemical modeling and laser diagnostics have been applied to these flames, and the ability to measure flame features, including temperature profiles and radical species concentrations, has been demonstrated, and will be discussed in terms of model development.