The Effect of MgO and MgO-Al2O3 on Zirconia Produced by Precipitation Method

The aim of this study is to produce partially stabilized zirconia with MgO and to investigate effect of Al2O3 on partially stabilized zirconia. Zirconia nanopowders are synthesized by the precipitation method from zirconium sulfate precursors. Precipitates are dried at 80 degrees C for 72 h and 2.77 in weight percentage MgO powders were added to dried powders. Then this powders mixture is calcinated at 1300 degrees C for 1 h. Furthermore, wt%10 Al2O3 is added to calcinated powders and two different powders mixtures are produced. Each powder mixture are pressed and sintered at 1650 degrees C for 1 and 2 h in an electrical resistance furnace. MgO-ZrO2 samples have cubic, tetragonal and monoclinic zirconia phases while alumina added MgO-ZrO2-Al2O3 samples have dominantly monoclinic zirconia and spinel phases. In MgO-ZrO2-Al2O3 samples, MgO dissolves in Al2O3 and therefore MgO in zirconia matrix is not enough for the stabilization. Microhardness and fracture toughness of MgO-ZrO2 samples are higher than that of MgO-ZrO2-Al2O3 samples.