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 α-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.