Synthesis of the ZrB_2-SiC Ceramic from Polymeric Precursor Pyrolysis

摘要

A ZrB_2-SiC multiphase ceramic was fabricated with a precursor pyrolysis method by using zirconium boride organic precursor and polycarbosilane. In order to study the pyrolysis process of complex phase ceramics, the pyrolysis process of the two precursors was studied respectively at the beginning. The precursor and the mixture with different weight ratios both pyrolyzed at 800°C ～1500°C. under argon atmosphere. The specimens were characterized by thermo-gravimetric analysis, infra-red, X-ray diffraction. It was found that the pyrolysis products of PCS remained amorphous below 1000°C and converted into crystallization with temperature increasing. ZrO_2 as the intermediate pyrolysis product of ZrB_2 precursor initiate convert to t-ZrO_2 from m-ZrO_2 at 1200°C. Finally, all kinds of ZrB_2-SiC multiphase ceramic are successful obtained via pyrolysis of precursor after 1500°C. And the 40wt%ZrB_2 precursor initial carbothermal reduction temperature below the ZrB_2 precursor reactive temperature and the crystal degree of SiC is higher than pyrolysis product of PCS.