Structure-function integrated ZrO₂-SiO₂ nanocrystalline glass-ceramics achieved by in situ formation of amorphous carbon

Ceramics can be traditionally classified as structural and functional ones. However, the miniaturization and multi-functionalization of various devices require ceramics to have both structural and functional properties. In this work, we aimed to develop structure-function integrated ZrO2-SiO2 nanocrystalline glass-ceramics (NCGCs) by in situ formation of homogenously distributed amorphous carbon. By reducing the calcination temperature of carbon-containing powder, organic carbon groups were partially retained in the powder and they transformed to amorphous carbon in the sintered NCGCs. At micrometer scale, the carbon was homogenously distributed in the NCGCs, avoiding the commonly encountered agglomeration problem of carbon fillers. The effects of carbon on the microstructure, mechanical properties, wear resistance, and dielectric properties of the NCGCs were investigated. Results showed that the in situ formed amorphous carbon was homogenously distributed in the ZrO2 nanocrystallites. Meanwhile, the amorphous carbon strongly bonded with the ZrO2-SiO2 NCGCs. Only a small amount of carbon was combusted even after annealing at 1000 degrees C for 3 h. The formation of amorphous carbon led to an improvement of nanohardness and wear resistance of the NCGCs, while slightly reducing Young's modulus and flexural strength. The electromagnetic wave transmission performances were improved due to the formation of amorphous carbon. The current study paves a new way for developing structure-function integrated glass-ceramics through in situ formation of carbon. The prepared structure-function integrated ZrO2-SiO2 NCGCs have great potential to be used as radome and antenna windows of aerospace aircrafts that work in harsh environment.