Zirconia stabilization assisted by high energy ball- milling

Abstract

Different zirconia (ZrO2) − x (x = CaO, ZnO mol%) solid solutions have been produced by high energy ball-milling (HEBM). The ZrO2 + oxide powder mixtures were milled for 15 and 25 hours, and thermal experiments were subsequently carried out. Experimental findings demonstrate a relationship of the powders’ morphology and crystal structure with zirconia stabilization. After the different milling times, X-ray diffraction (XRD) studies did not show any sign of zirconia stabilization; however, after thermal experiments total cubic ZrO2-CaO stabilization was obtained. According to the lattice parameter measurements, solid solutions were formed with the oxides and zirconia powders during the HEBM. These results did not show zirconia stabilization in the ZnO2 addition case. Both scanning electron microscope (SEM) and XRD structural observations indicate greater crystalline structural deformation of the ZrO2-ZnO high energy ball-milled powders in comparison to that of the ZrO2-CaO powders. Furthermore, the behaviors in the lattice parameter values of the ZrO2-CaO system showed a tendency toward increasing the monoclinic symmetry of the cell, which could be beneficial in obtaining total zirconia stabilization (TZS). In the dilatometer and XRD experiments monoclinic (m)→cubic (c) (CaO) or m→tetragonal (t) (ZnO) temperature changes for each oxide addition to zirconia were observed.