A thermoset hybrid sol for the syntheses of zirconium carbide–silicon carbide foam via replica method

Abstract

Zirconium carbide–silicon carbide (ZrC–SiC) ceramics are amongst the promising candidate materials for thermal protection structures in hypersonic re-entry space vehicles. A thermoset hybrid sol for the syntheses of monolithic ZrC–SiC composites was prepared by a simple sol–gel method. Furfuryl alcohol, polyzirconoxane and tetraethyl orthosilicate were used as raw materials. The as-synthesized sol can be cured at 85 °C for 24 h to obtain a bulk gel. The cured gel is converted into porous ZrC–SiC monolith with porosity of 44.1% after pyrolysis at 1500 °C for 1 h in vacuum. The ZrC–SiC monolith is composed of well distributed nano-sized ZrC and SiC particles. Highly porous ZrC–SiC ceramic foam with density of 0.34 g/cm3 and porosity of 78.1% is prepared by replica method using the hybrid sol as precursor and melamine foam as templates. The hybrid sol and ZrC–SiC composites are characterized by FT-IR, TG–DTA, XRD, SEM, EDS and TEM.