Achieving robust mechanical properties and high translucence in ZrO2-SiO2-Al2O3 ternary ceramic nanocomposites

Transparent or translucent ceramics typically exhibit inferior mechanical performance, which restricts their wider application. Here, we aim to develop ZrO2-SiO2-Al2O3 ternary ceramic nanocomposites (TCNCs) that integrate those two often incompatible properties via microstructure engineering. A fixed ratio of 30 mol% SiO2 was introduced into the ZrO2-Al2O3 system, while the ratios between ZrO2 and Al2O3 were varied. Additionally, different forms of Al2O3 (crystallization or amorphous) were used, resulting in four types of TCNCs. Among the samples studied, the TCNC containing 60 mol% ZrO2 and 10 mol% amorphous Al2O3 achieved high translucency and remarkable mechanical properties. The TCNC comprised ZrO2 nanoparticles embedded in SiO2 glass matrix and Al2O3 glass domains. The superior properties of the TCNC can be attributed to its nanocrystalline-amorphous dual-phase microstructure. For TCNCs utilizing alpha-Al2O3 submicron particles as the aluminum source, despite their adequate mechanical properties, the agglomeration and lack of densification of these particles resulted in significant light scattering, rending the TCNCs opaque. This study demonstrates that engineering a nanocrystalline-amorphous dual-phase microstructure is an effective strategy to achieve a synergistic combination of robust mechanical properties and high translucence.