NANOCOMPOSITE SI/C/N POWDER PRODUCTION BY LASER-AEROSOL INTERACTION

Ultrafine preceramic Si/C/N powders were obtained via ultrasonic injection of aerosol particles into a high-power CO2 laser beam, using hexamethyldisilazane, which strongly absorbs the CO2 laser radiation at 10.6 mum, as the precursor. Introduction of aerosol droplets via a flowing argon or argon-NH3 mixture into the laser beam yielded nanosized (30 to 60 nm), amorphous powders. Yield and particle composition were controlled by varying the synthesis conditions. Powder changes, such as crystallization during heat treatment under nitrogen or argon, were studied.