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

Abstract

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.