FLAME AEROSOL SYNTHESIS OF CERAMIC POWDERS

Flame aerosol technology is used for large-scale manufacture of cerami c commodities such as pigmentary titania, fumed silica and alumina. In addition, the introduction of this technology to the manufacture of o ptical fibers and its potential for cheap synthesis of ultrafine parti cles (e.g. nanoparticles) has renewed the research interest for better understanding of flame aerosol reactors. Here, after an overview of t he history of this technology, the current state of knowledge on the r ole of flame process variables (additives, mixing etc.) on the charact eristics of product powders is summarized in a tutorial fashion. The f undamentals of particle formation and growth are highlighted by summar izing the dynamics of spherical particles that are reasonably well und erstood. The latest advances on the theory of aggregate particle dynam ics that are typically encountered in flame synthesis of powders are p resented. Specific applications in the manufacture of fumed si!ica, pi gmentary titania, alumina, and other oxide and non-oxide ceramic powde rs are reviewed. Finally, research needs are highlighted by pointing o ut the most promising areas for advancing the field with emphasis on i nstrumentation and need for detailed simulators of the process account ing for the concurrent chemistry, transport and aggregate particle dyn amics. With major recent advances in diagnostics and understanding in both combustion and aerosol science and engineering, this field is rea dy for a new leap forward. (C) 1998 Elsevier Science Ltd. Ail rights r eserved.