Improved ageing-resistance and fracture toughness of zirconia-toughened alumina bioceramics via composition and microstructure design

Low-temperature degradation (LTD) is the main obstacle that hinders the application of zirconia-toughened alumina (ZTA) ceramics as artificial hip joints. In this study, a new type of ZTA bioceramic with LTD resis-tance, high fracture toughness, and superior wear resistance was prepared by the in-situ formation of plate-like crystals and co-stabilised tetragonal phase zirconia (t-ZrO2). This new design is realised by synthesising nano-crystalline PrAlO3 through a one-step solution combustion method and introducing it into a ZTA matrix to form praseodymium hexaaluminate (Pr0.833Al11.833O19, PHA) plate-like crystals by solid-state sintering. PHA plays a key role in toughening and Y-Pr co-doped t-ZrO2 slows down the low-temperature degradation of ZTA bio-ceramics. After hydrothermal ageing, the combination strategies have a positive influence on the flexural strength, fracture toughness, and Vickers hardness of the ceramics. This study provides a novel direction for ensuring long-term safety of bioceramics.