The Effect of MgO and MgO-Al_2O_3 on Zirconia Produced by Precipitation Method

摘要

The aim of this study is to produce partially stabilized zirconia with MgO and to investigate effect of Al_2O_3 on partially stabilized zirconia. Zirconia nanopowders are synthesized by the precipitation method from zirconium sulfate precursors. Precipitates are dried at 80 °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 °C for 1 h. Furthermore, wt%10 Al_2O_3 is added to calcinated powders and two different powders mixtures are produced. Each powder mixture are pressed and sintered at 1650 °C for 1 and 2 h in an electrical resistance furnace. MgO-ZrO_2 samples have cubic, tetragonal and monoclinic zirconia phases while alumina added MgO-ZrO_2-Al_2O_3 samples have dominantly monoclinic zirconia and spinel phases. In MgO-ZrO_2-Al_2O_3 samples, MgO dissolves in Al_2O_3 and therefore MgO in zirconia matrix is not enough for the stabilization. Microhardness and fracture toughness of MgO-ZrO_2 samples are higher than that of MgO-ZrO_2-Al_2O_3 samples.