Synthesis of Composite Particles by Liquid Aerosol Thermolysis

Liquid aerosol thermolysis (LAT) refers to the general class of particle synthesis processes in which a liquid precursor solution is atomized into discrete droplets and subsequently transported through a time/temperature/atmosphere-regulated reactor. The overall objective of the proposed program is to establish a fundamental engineering science for the synthesis of submicron, composite particles by liquid aerosol thermolysis. Particle synthesis and solution experiments are designed to identify those factors affecting solid composite particle formation and chemical distribution. In situ technique will be used to monitor droplets generation and shrinkage during the evaporation stage as a function of atomization, precursor solution characteristics and evaporation conditions. After the evaporation stage, on-line sampling will be used to obtain and characterize particles as a function of time and temperature. Each process step will be mathematically analyzed using information generated in the above experiments and evaluated against existing or derived models for those processes. Model systems, based on alumina precursors as the matrix phase, have been selected examine first the synthesis of homogeneous composite systems in which the nanocrystalline phases are uniformly dispersed and second, those in which one phase encapsulates the other. Zinconia and platinum in alumina allow use to examine issues associated with uniform precipitation whereas alumina-SiC allows us the possibility to examine the isolation of one phase (SiC) within another (i.e. intragranular). The proposed techniques aim to production of nanocrystalline materials of a wide compositional range and having 100 nm crystallinity, of desired uniformity and second phase distribution.