Formation and Growth of Silicon Nitride Particles in a Laser-Driven Aerosol Reactor Investigated with Photon Correlation Spectroscopy and Electron Microscopy

ABSTRACT

This paper investigates the formation and growth of silicon nitride particles in a laser-driven aerosol reactor. This investigation is done on-line with photon correlation spectroscopy (PCS) and off-line with electron microscopy. The results of the measurements are compared with each other and with a monodisperse growth model that incorporates the influence of particle shape. PCS proved to be a good and fast monitoring technique, but it provides limited information: the intensity-weighted average particle size and approximate velocity. Electron microscope studies of samples showed good agreement with both the spectroscopy and the modeling results. The incorporation in the model and in the determination of the PCS diameter of the extra information about particle size and phase from the electron microscope photographs increases their accuracy. This is necessary if PCS combined with growth model are to be used for process control. Although the analysis techniques and the model are applied to a specific case, they are applicable in all types of flame reactors.