Synthesis and characterization of a polyborosilazane/Cp2ZrCl2 hybrid precursor for the Si-B-C-N-Zr multinary ceramic

A novel zirconium-contained polyborosilazane (PBSZ-Zr) was synthesized by chemical modification of a liquid polyborosilazane (LPBSZ) with Cp2ZrCl2. A Si-B-C-N-Zr multinary ceramic was prepared via pyrolysis of PBSZ-Zr. The properties and the ceramization process of PBSZ-Zr, as well as the microstructural development and properties of the derived SiBCN-Zr ceramic, were well studied. The active Si-H and N-H groups in LPBSZ react with Zr-Cl in Cp2ZrCl2 to form PBSZ-Zr polymers. The Zr content of the SiBCN-Zr ceramic was 3.39 wt% when the weight ratio of Cp2ZrCl2 to LPBSZ was 20 : 100. The SiBCN-Zr ceramic remains amorphous when pyrolyzed below 1600 °C, but the crystal phases of Zr2CN, ZrC, BN, SiC, and Si3N4 were detected from a 1600 °C treated sample. Due to the low activity of free carbon at the interface of the SiBCN-Zr ceramic, the oxidation resistance of the SiBCN-Zr ceramic under air was improved compared with the SiBCN ceramic.