Characterization of CaO-ZrO$_{2}$ and CaO-ZrO$_{2}$-Al$_{2}$O$_{3}$

Abstract

This study is focused on production of partially stabilized zirconia containing 8 mol % CaO and examination of effect of Al$_{2}$O$_{3}$ adding on it. Zirconia nanopowders were synthesized by the precipitation method from zirconium sulfate precursors. Precipitates were dried at $80\,^{\circ }$C for 72 h, and CaCO$_{3}$ powders were added to dried powders. Then this powder mixture was calcinated at $1300\,^{\circ }$C for 1 h. And the second powder mixture was prepared by adding wt.%10 Al$_{2}$O$_{3}$ to calcinated powders. Each powder mixture were pressed under uniaxial compression of 300 MPa and sintered at $1600\,^{\circ }$C for 1 and 2 h in an open atmospheric electrical resistance furnace. Relative densities of sintered samples measured in terms of Archimedes’ principle were about 99 % for CaO-ZrO$_{2}$ and 97.5 % for CaO-ZrO$_{2}$-Al$_{2}$O$_{3}$. XRD analysis revealed that sintered CaO-ZrO$_{2}$ has monoclinic, tetragonal or/and cubic zirconia and sintered CaO-ZrO$_{2}$-Al$_{2}$O$_{3}$ has similar phases to CaO-ZrO$_{2}$ has, differently include CaAl$_{12}$O$_{19}$ phase. SEM-EDS analyses showed that the sintered samples have inhomogeneous grain structure and calcia was only dissolved in large zirconia grains. This means that calcia promoted grain growth of zirconia particles.