Le Fu,Bohan Wang,Junjie Song,Chenglong Xu,Guofu Xu,Qiuan Sun,Jiwu Huang,Håkan Engqvist,Wei Xia
The content of crystalline phase plays a significant role in manipulating the microstructure and mechanical properties of glass-ceramics. This study aims at exploring the optimum content of crystalline phase in ZrO 2 –SiO 2 nanocrystalline glass-ceramics (NCGCs) in terms of obtaining the highest mechanical properties. To this end, the mechanical properties of ZrO 2 –SiO 2 NCGCs with 70 mol%, 75 mol%, 80 mol% ZrO 2 were tested and compared with those of the previously prepared NCGCs with ZrO 2 content ranging from 35 mol% to 65 mol%. Results showed that 65 mol% was the optimum content of ZrO 2 in terms of obtaining the highest flexural strength . The flexural strength of NCGCs with ZrO 2 content over 65 mol% was lower than that of the NCGCs with 65 mol% ZrO 2 . This was because the NCGC with 65 mol% ZrO 2 had a homogenous microstructure, with ZrO 2 nanocrystallites homogeneously distributed in an amorphous SiO 2 matrix. Whereas, when ZrO 2 content was increased to 75 mol%, ZrO 2 nanocrystallites were not homogeneously distributed in the SiO 2 matrix anymore. The formation of SiO 2 “holes/canyon” due to ZrO 2 grain coalescence resulted in the decrease of flexural strength. The fracture mechanism and wear properties of the NCGCs were also investigated.
Wenjun Yu,Zihua Lei,Xiaoyu Zhang,Qinzhao Zhang,Yongxing Cheng,Ying Deng,Yang Li,Junjie Song,Le Fu
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 ZrO 2 –SiO 2 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 ZrO 2 nanocrystallites. Meanwhile, the amorphous carbon strongly bonded with the ZrO 2 –SiO 2 NCGCs. Only a small amount of carbon was combusted even after annealing at 1000°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 ZrO 2 –SiO 2 NCGCs have great potential to be used as radome and antenna windows of aerospace aircrafts that work in harsh environment.
危险品化学品经营许可证（带存储）