Phase development in metal-dropped silicon oxycarbides under water vapor and argon hybrid atmosphere

In this study, metal-modified silicon oxycarbides ceramics (SiOC/M, M = Fe, Al, and Zr) were fabricated, and the thermal stability of the SiOC/M (M = Fe, Al, and Zr) ceramics was investigated under the water-vapor- argon hybrid atmosphere. The phase and microstructural analysis showed that the thermal stability was in the order of SiOC/Zr ＞ SiOC/Al > SiOC/Fe. The SiOC/Zr and SiOC/Al ceramics possessed better thermal stability than SiOC/Fe ceramics, because they formed metallic oxides (ZrO2, mullite, or sillimanite). Additionally, the water-vapor-argon hybrid atmosphere increases the defects within the carbon clusters of SiOC/M ceramics and refines the lateral size of the nanocrystalline carbon. Understanding thermal stability and microstructural evolutions of metal-dropped polymer derived ceramics provided a new method for achieving high-temperature ceramics for application in an extreme environment.