Effect of ZrC content on the properties of biomorphic C-ZrC-SiC composites prepared using hybrid precursors of novel organometallic zirconium polymer and polycarbosilane

摘要

A novel organometallic zirconium polymer was synthesized through the copolycondensation using n-butyllithium, 1,4-diethynylbenzene, phenylacetylene and zirconium tetrachloride as raw materials. Then biomorphic C-ZrC-SiC composites were fabricated from corn stover templates by precursor infiltration and pyrolysis process using hybrid polymeric precursors containing the organometallic zirconium polymer and polycarbosilane. The microstructure, mechanical properties and oxidation resistance of the composites were investigated. With ZrC content increasing, the mechanical properties of the composites were enhanced due to dispersion strengthening and grain fining of the homogeneously dispersed ZrC nanoparticles. The oxidation behavior of C-SiC-ZrC indicated that the oxidation resistance of the composite was reduced at 1000 degrees C but improved at 1500 degrees C with the increase of ZrC content. The improved oxidation resistance was mainly attributed to a proper ZrC content, the formation of ZrSiO4 layer on the surface of the composite, and its matrix microstructure characterized by a nano-sized dispersion of ZrC-SiC phases.