Inter-granular phase formation and flexural strength of MgO partially stabilized zirconia by Al2O3 additions

Phase transformation and inter-granular phase formation of 9 mol% MgO partially stabilized zirconia (Mg-PSZ) according to Al2O3 addition were investigated in terms of crystallography and morphology, and its flexural strength was measured. Sintered bulk specimens of 9 mol% Mg-PSZ ball-milled with Al2O3 (1, 5, 10 mol%) were evaluated by X-ray diffraction, transmission electron microscopy and EDS. Monoclinic phase in Mg-PSZ, which has a larger lattice than that of cubic and tetragonal phases, increased as a function of Al2O3 addition. The apparent density of Mg-PSZ was decreased with increasing Al2O3 addition, and flexural strength was also exibited the lowest value with 10 mol% Al2O3 addition. Mg-rich phase, forsterite (Mg2SiO4), and spinel (MgAl2O4) were observed along grain boundary of Mg-PSZ with Al2O3 additon by TEM-EDS. It was considered that destabilization of Mg-PSZ by Al2O3 addition led to decrease the apparent density, and countinuous inter-granular phase formation caused the decrease of flexural strength.