THERMAL-BEHAVIOR OF POLYMER-DERIVED CERAMICS .4. SI-C-N-O FIBERS FROMAN OXYGEN-CURED POLYCARBOSILAZANE

Fibered Si-C-N-O-based ceramics from a polycarbosilazane precursor (co polymer) are studied, then compared to other ceramic materials previou sly prepared and described in other papers. The emphasis is upon the s tructural and textural features as observed by high-resolution transmi ssion electron microscopy and their evolution with an increasing heat- treatment temperature up to 1600-degrees-C. Both argon or nitrogen atm ospheres were used. Specifically, the peculiar behavior of the materia l during the amorphous to crystalline transition until degradation is revealed. The consequences on the nucleation and the growth of the SiC grains, and the electrical and mechanical properties are discussed.