LAUSR

Abstract The high-temperature behavior of an electrically conductive, opaque and hard Hf7B23Si22C6N40 ceramic film with an amorphous structure was systematically investigated in air up to 1700 °C and inert gases up to 1600 °C. The film was prepared by reactive pulsed dc magnetron sputter deposition in an argon‑nitrogen gas mixture. The study is focused on the oxidation resistance of the film and the evolution of the structure, microstructure and elemental composition upon annealing in air and argon, and on the thermal stability of its hardness and electrical resistivity upon annealing in helium. The film exhibits an excellent oxidation resistance up to 1600 °C due to the formation of a compact protective oxide surface layer with a nanocomposite structure consisting of monoclinic and tetragonal/orthorhombic HfO2 nanocrystallites surrounded by a SiO2-based amorphous matrix. The film itself crystallizes into several phases such as HfB2, HfC0.5N0.5 and α-Si3N4 upon annealing but its elemental composition remains unaffected up to 1600 °C. In addition, the hardness and electrical resistivity exhibit also very high thermal stability.