FORMATION AND GROWTH OF SILICON-NITRIDE PARTICLES IN A LASER-DRIVEN AEROSOL REACTOR INVESTIGATED WITH PHOTON-CORRELATION SPECTROSCOPY AND ELECTRON-MICROSCOPY

This paper investigates the formation and growth of silicon nitride pa rticles in a laser-driven aerosol reactor. This investigation is done on-line with photon correlation spectroscopy (PCS) and off-line with e lectron 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 monitori ng technique, but it provides limited information: the intensity-weigh ted average particle size and approximate velocity. Electron microscop e studies of samples showed good agreement with both the spectroscopy and the modeling results. The incorporation in the model and in the de termination of the PCS diameter of the extra information about particl e size and phase from the electron microscope photographs increases th eir accuracy. This is necessary if PCS combined with growth model are to be used for process control. Although the analysis techniques and t he model are applied to a specific case, they are applicable in all ty pes of flame reactors. (C) 1997 American Association for Aerosol Resea rch.