Structural evolution and oxidation resistance of polysilazane‐derived SiCN–HfO2 ceramics

Abstract

AbstractPolymer‐derived SiCN materials have great application potential in high‐temperature environments. In the current work, SiCN ceramics were tailored with Hf incorporation through doping of a molecular precursor in the preceramic polymer. The ceramics remained in a single amorphous phase up to 900°C. Further annealing caused nucleation and crystallization of tetragonal hafnium oxide (t‐HfO2) within the SiCN matrix, resulting in a unique glass–ceramic nanocomposite of t‐HfO2–SiCN. The crystal sizes of t‐HfO2 were in the range of 2.3–5.1 nm. Raman spectroscopy was employed to examine the effect of Hf‐doping on the phase separation and crystallization of sp2‐carbon. Thermal stability in an oxidizing environment was analyzed by thermogravimetry. The incorporation of Hf in the SiCN ceramic system led to improved phase stability and oxidation resistance compared to the undoped SiCN system.