Preparation and properties of lanthana doped ZTA ceramics with plate-like crystals by microwave sintering

Lanthana doped zirconia toughened alumina (ZTA) ceramics with in situ formation of plate-like crystals have been prepared by microwave sintering derived from ZrOCl2 center dot 8H(2)O, Al(NO3)(3)center dot 9H(2)O and La(NO3)(3)center dot 6H(2)O. Samples were detected for phase analysis by X-ray diffraction, and the microstructure was examined using SEM. In addition, the sintering behaviour and mechanical properties (hardness and fracture toughness) of the ZTA material were investigated. Results show that LaAl11O18 plate-like crystals are formed in situ in the ZTA matrix when a certain amount of La2O3 is added, and the quantity, size, dispersion degree and crystallite growth of LaAl11O18 crystals are greatly influenced by microwave sintering. Compared to traditional sintering, samples obtained by microwave sintering possess improved performances. The optimal mechanical properties are achieved by doping of 1.5 mol.-%La2O3, with fracture toughness and Vickers hardness being 7.1 MPa m(1/2) and 17.2 GPa respectively.