A simple way to prepare a precursor for ZrC–SiC ceramics

For cost reduction and process simplification, a homogenous liquid precursor for zirconium carbide (ZrC)–SiC ceramics was prepared by blending Zr(OC4H9)4, divinylbenzene, and polycarbosilane (PCS). The mixture was cross-linked at 150 °C, decomposed to ZrO2, carbon, and SiC at 800 °C, and then ZrO2 and carbon reacted with each other via carbo-thermal reaction at 1500 °C to form ZrC–SiC ceramics that contained few ZrO2. The ZrO2 content was reduced either by increasing the temperature from 1500 to 1700 °C, or by extending the holding time from 1 to 2 h. Increasing the content of PCS in the precursor not only benefited the carbo-thermal reaction but also caused the generation of free carbon in the pyrolyzed ceramic products. When the precursor contained the optimal content of PCS, the ceramics fabricated from it had a Si/Zr molar ratio of 1. C/ZrC–SiC composites were successfully fabricated via precursor infiltration and pyrolysis using the precursor. The flexural strength and fracture toughness of the composites were 212 ± 44 MPa and 13.8 ± 1.6 MPa m1/2, respectively.