Understanding microstructure-mechanical properties relationship in ZrO2–SiO2 nanocrystalline glass-ceramics: The effect of ZrO2 content

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.