In ammonia pyrolytic process of polysilazines via reactions of hydrazine with MeHSiCl2 (or Me(CH2CH)SiCl2) followed by crosslinking treatment to obtain PHSZ and PVSZ respectively

was traced by combining TG GC

IR

XRD

elemental analysis

and density measurement.Below 673K N—N breakage and transamination occurred in PHSZ and PVSZ

yielding Si—NH2 containing end groups and N2H4 release

while Si—H bonds in PHSZ were nucleophilic substituted to form Si—NH2 and release H 2.At higher temperatures Si—C

C-C

C-H

N-H breakages occurred simultaneously to form radicals (≡Si·

≡C·

·NH2)

followed by radicals'transference and combination to remove alkyl or alkeneyl groups via releasing H2.CH4

C2H4

C2H6

etc.

thus leading to inorganic structures with negligible carbon content above 873K.The amorphous pyrolyzates were obtained when heat treatment temperatures were lower than 1673K

and microcrystalline Si3N4 at 1873K.