Zirconia Toughened Alumina Ceramics via Forming Intragranular Structure

The distribution of second phase particles in the microstructure of composite ceramics affects the mechanical properties, and the intragranular structures often result in better properties compared to the intergranular structures. However, it is difficult to obtain composite ceramics with intragranular structure by conventional route. To produce composite ceramics with an intragranular structure in a simpler route. In this work, starting powders with different phase compositions were obtained by the co-precipitation method, and zirconia toughened alumina (ZTA) composite ceramics were prepared with these starting powders by spark plasma sintering (SPS). The results show that it is easier to fabricate ZTA composite ceramics with an intragranular structure by using composite powders containing amorphous or transition phase Al₂O₃ as starting materials. The phase composition of the powder prepared by the co-precipitation method after calcination at 1100 °C is θ-Al₂O₃ and t-ZrO₂, and the average grain size after sintering at 1500 °C is 1.04 ± 0.28 µm, and the maximum Vickers hardness and fracture toughness of the specimens reach 19.37 ± 0.43 GPa and 6.18 ± 0.06 MPa·m^1/2, respectively. The ZrO₂ particles were the core of crystallization and grow together with the Al₂O₃ matrix, forming the intragranular structure of ZTA ceramics. This work may provide a new idea for preparing composite ceramics with intragranular structure.