A containerless melting-solidification strategy to fabricate ZrO2-Al2O3-SiO2 ternary ceramic composites containing crystalline and amorphous phases

The limited flexibility in terms of chemical composition restricts the microstructure and property regulation possibilities of ZrO 2 -Al 2 O 3 binary ceramic composites (BCCs). Therefore, it is significant to prepare ternary ceramic composites by introducing a third phase. In this study, a fixed proportion of amorphous SiO 2 (30 mol%) was incorporated as the third phase to develop ZrO 2 -Al 2 O 3 -SiO 2 ternary ceramic nanocomposites (TCNCs) with two distinct Zr/Al ratios. The TCNCs were fabricated using containerless aerodynamic levitation technology, which featured a large thermal gradient that would facilitate the formation of nano-eutectics. In samples with a Zr/Al ratio of 3:1, monoclinic ZrO 2 was the sole crystalline phase. The Al element was present in either Al-O-Si or Al-O glass phase, depending on the processing temperature; In contrast, ZrO 2 -Al 2 O 3 nano-eutectics were formed in samples with a Zr/Al ratio of 3:8, accompanied by the generation of mullite crystallites. The SiO 2 phase functioned as an amorphous matrix. Vickers hardness of the TCNC with a Zr/Al ratio of 3:8 exhibited comparability to that reported for ZrO 2 -Al 2 O 3 composites.