Stepwise synthesis of a Zr-C-Si main chain polymer precursor for ZrC/SiC/C composite ceramics.

Abstract

Novel polymers containing a refractory metal in the main chain are highly desired as ultra-high temperature ceramic precursors. Herein, a low oxidation state active species Cp2Zr(ii) with two semi-filled outer orbits was firstly obtained using Cp2ZrCl2 with Mg. This active species of Cp2Zr(ii) was subsequently copolymerized with (CH3)2Si(CH2Cl)2 to form a PZCS precursor with a Zr–C–Si main chain. The pathways of constructing the Zr–C–Si main chain were proposed based on the active species Cp2Zr(ii) polymerization combined with the auxiliary function of ·MgCl, quite different from the conventional understanding of using the Grignard reaction mechanism to explain the synthesis of metal-containing polymer precursors. The ceramic yield of the PZCS precursor at 900 °C is 43.9 wt%, and the ZrC/SiC/C composite preceramic powder was prepared by the pyrolysis of the PZCS precursor, which has important application prospects in ultra-high sonic aircraft and aero rocket engines. It is expected that this stepwise method of using refractory metal-containing active species to synthesize main-chain metallopolymers would provide significant guidance for preparing novel UHTCs precursors.