Investigation of the Effect of Supersonic Flow of Dissociated Nitrogen on ZrB2–HfB2–SiC Ceramics Doped with 10 vol.% Carbon Nanotubes

Abstract

The method of fabricating dense ultra-high temperature ceramic materials ZrB2–HfB2–SiC–CCNT was developed using a combination of sol-gel synthesis and reaction hot pressing approaches at 1800 °C. It was found that the introduction of multilayer nanotubes (10 vol.%) led to an increase in the consolidation efficiency of ceramics (at temperatures > 1600 °C). The obtained ZrB2–HfB2–SiC and ZrB2–HfB2–SiC–CCNT materials were characterized by a complex of physical and chemical analysis methods. A study of the effects on the modified sample ZrB2–HfB2–SiC–CCNT composition speed flow of partially dissociated nitrogen, using a high-frequency plasmatron, showed that, despite the relatively low temperature established on the surface (≤1585 °C), there was a significant change in the chemical composition and surface microstructure: in the near-surface layer, zirconium–hafnium carbonitride, amorphous boron nitride, and carbon were present. The latter caused changes in crucial characteristics such as the emission coefficient and surface catalyticity.