Preceramic Polymer Pyrolysis. 1. Pyrolytic Properties of Polysilazanes

摘要

The physicochemical behavior of characterized polysilazanes has been examined during their pyroltic transformation into amorphous, silicon based, ceramics. Selected polysilazanes, bearing different substituents at silicon and nitrogen were synthesized by ruthenium catalyzed dehydrocoupling of Si-H bonds with N-H bonds. The relationships between the structure and chemical content of polymers and their pyrolyzed ceramic compositions and yields are discussed. The thermal reactivity during the pyrolysis is established by a set of hypothetical mechanisms that may occur during the heating process. The decomposition product patterns at different temperature levels and the compositions of the final ceramics suggest specific kinetically or thermodynamically controlled thermolysis pathways. Additional chemical reactivity has been observed when the amorphous ceramic products at 800 C are heated and crystallized at 1600 C.