Synthesis and characterization of SiC/MC/C ceramics (M = Ti, Zr, Hf) starting from totally non-oxidic precursors

The reaction of poly(dimethylsilane) (PDMS) and poly(dimethylcarbosilane) (PCS) with bis(cyclopentadienyl)M dichloride CP2MCl2 (M = Ti, Zr, Hf) complexes has been used as a new route to obtain ceramic materials based on SiC-containing M. The reaction is completed at a relatively low temperature, 900 degreesC, yielding the corresponding amorphous SiC/MC ceramics which have been characterized by means of Si-29 MAS NMR. These amorphous materials have been treated at higher temperatures, 1350 degreesC, under a purified argon atmosphere, yielding partially crystallized products which have been studied by X-ray powder diffraction and Si-29 HAS NMR. The effect of the composition of the mixture of precursors is also studied in this work.