Laser synthesis and crystallization of nanocomposite Si/C/N powder

Ultrafine preceramic Si/C/N composite powders have been prepared from hexamethyl-disilazane (HMDS) by laser-induced gas phase reaction, using a new kind of two-reaction-zone reactor which could efficiently increase laser efficiency and production yield compared with a one-reaction-zone reactor. The as-formed products were nanosized (50-80 nm), amorphous powders containing Si-C and Si-N bonds homogeneously mixed with some excess carbon. The production yield was in the range of 88-120 g/h. Changes of chemical composition and crystallization of the powders during heat treatment at 1350 and 1550°C under nitrogen for 1 h were studied.