Fate of polymer derived SiC monolith at different high temperatures

Abstract

Monolithic polymer-derived SiC is highly desirable for high temperature applications because of its unique thermal properties in extreme conditions. The current study focuses on the formation, evolution, and stability of polymer-derived SiC at different high temperatures. SiC-based monoliths were pre-pyrolyzed at 1200 °C and then pyrolyzed at 1600 - 2500 °C in a flowing argon atmosphere. The porosity, density, compositions, and phases of the SiC samples were studied. Dense SiC monolith was obtained from 1200 °C to 2200 °C. SiC crystallized at 1900 °C and formed a near stoichiometric composition. β-SiC remained stable even at 2200 °C. However, the SiC monolith experienced continuous mass loss above 1900 °C and disintegrated at 2500 °C with ∼89.5% mass loss. This work opens a pathway for preparing near stoichiometric and dense SiC monoliths through polymer precursor pyrolysis; it also provides fundamental understanding of polymer-derived SiC at different high temperatures.