Synthesis of ZrC-SiC Powders from Hybrid Liquid Precursors with Improved Oxidation Resistance

ZrC-SiC powders are synthesized by high-temperature pyrolysis of hybrid liquid precursors, which are prepared from organic Zr-containing precursor (PZC) and liquid polycarbosilane (LPCS). Due to the excellent miscibility between PZC and LPCS, the hybrid liquid precursors are formed by dissolving PZC into LPCS without adding organic solvent. The viscosity and elemental content of Zr and Si of the hybrid precursors are readily adjustable by controlling the LPCS/PZC mass ratio. SEM and TEM observations reveal that the ZrC-SiC powders pyrolyzed at 1550 degrees C exhibit spherical morphology with characteristic dimension of less than 60nm, and the two phases are uniformly distributed in composite powders. The advantage of the ZrC-SiC powders synthesized by this novel method is demonstrated by investigating the oxidation behavior of powders with different amount of SiC and ZrC. Below 700 degrees C, ZrC quickly oxidizes to generate an almost nonprotective ZrO2 scale, whereas at similar to 1000 degrees C, dense and protective SiO2 forms that improves the oxidation resistance of the ZrC-SiC composite powders.