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

Ultrafine preceramic Si/C/N powders were obtained via ultrasonic injec tion of aerosol particles into a high-power CO2 laser beam, using hexa methyldisilazane, which strongly absorbs the CO2 laser radiation at 10 .6 mum, as the precursor. Introduction of aerosol droplets via a flowi ng argon or argon-NH3 mixture into the laser beam yielded nanosized (3 0 to 60 nm), amorphous powders. Yield and particle composition were co ntrolled by varying the synthesis conditions. Powder changes, such as crystallization during heat treatment under nitrogen or argon, were st udied.