he pyrolytic properties of polysilazane (PSZ)

synthesized from ammonolysis of mixture of halosilanes

in N2 or NH3 atmosphere have been studied.The result showed that PSZ can be convertedinto amorphous ceramics through three pyrolytic process in N2 atmosphere and a composite of a-Si3N4 crystal and β-SiC microcrystal at higher temperature. The β-SiC is formed by the pyrolysis of Si-CH3 group

therefore. the content of Si3N4 in ceramics can be increased by decreasing of Si-CH3 group in PSZ. When pyrolyzed in NH3 atmosphere

the process of carbon removal takes place

resulted in the formation of an amorphous inorganic materials which transformed into almost pure a-Si3N4 crystal at 1500℃.