Fabrication and characterization of precursor-derived non-oxide ZrC-SiC multiphase ultrahigh temperature ceramics

ZrC-SiC multiphase ceramics are the most promising candidates as ultra high temperature ceramics for aerospace applications. In this work, preceramic polymers with tunable compositions have been synthesized by hydrosilylation reactions. FTIR and NMR spectra illustrate that the Zr-N bonds are formed by Zr-Cl and N-H replacement for an incomplete extent. Then Grignard reagent (allyl-MgCl) is used to consume the residue Zr-Cl bonds and tailor the structure of the precursors. The meliorated ZrNCSi precursors have higher ceramics yields and good solubility. Annealing experiments of the derived ZrC-SiC ceramics in an inert atmosphere at temperatures in the range of 1400-2000 degrees C show good high temperature resistance. The precursor-derived ZrC-SiC multiphase ceramics get dense with well dispersed nano ZrC crystallites when temperature rises. Oxidation test indicates that the ceramics have postponed oxidation process at low temperature and could keep stable at high temperature (1700 degrees C) with the formation of oxidation layer at the surface. (C) 2016 Elsevier Ltd. All rights reserved.