Preparation of ZrC-SiC multiphase ceramics by pyrolysis of polyzrocarbonane/ polycarbosilane hybrid precursor

The ZrC-SiC multiphase ceramic precursor of PZCS with abundant active cross-linking sites was prepared by a dehydrocoupling reaction between polyzrocarbonane (PZC) and polycarbosilane (PCS). The ceramization mechanism of PZCS and the composition and structure of the final ceramic were studied. The results reveal that the ceramic yield of PZCS (71.84%, mass fraction, the same below) is significantly higher than that of PZC (51.40%) or PCS (53.46%) precursor at 850 ℃, due to the promoted crosslinking of active groups during the ceramization process. Meanwhile, under the catalysis of Zr-Cp, the short-range carbon and Zr, Si elements are directly converted to carbide ceramics through the synergistic transformation of two polymers in PZCS, avoiding the adverse effects of carbon thermal reduction to the ceramics, and effectively reducing the sintering temperature. The ZrC-SiC nanocomposite ceramic with both high temperature resistance and oxidation resistance components is prepared after pyrolysis of PZCS. The generation of ZrC and SiC phases could inhibit crystallization and refine the grain size, of which the ZrC grain size is 25.4 nm. Moreover, the generation of ZrC-SiC nanocomposite structure would be beneficial for improving the comprehensive performance of ultra-high temperature ceramics.