Effect of magnesia rich spinel on densification and stabilization behavior of monoclinic zirconia

Fully cubic-stabilized zirconia ceramic composites have been successfully fabricated by conventional sintering technique using commercial monoclinic zirconia, Yttrium oxide and waste-derived magnesia-rich spinel (MMA) powder mixtures. In this study, effect of MMA content and sintering temperature on stabilization and densification properties of zirconia has been duly considered. The obtained results showed that m-ZrO2 in MMA-free Z0 reference specimen is partially stabilized upon temperature rising into tetragonal phase by Y3+ ions diffusion inside zirconia structure. MMA-free Z0 reference specimen sintered at 1600 oC showed m- and t-ZrO2 dual-phase structure with a relative density of 80.2%. Unlike, upon rising the sintering temperature, Z10–Z50 composites containing 10–50 wt% MMA demonstrated higher relative density of more than 99% and showed variant behavior, where their m-ZrO2 is transformed and stabilized into cubic form by diffusion of Y3+, Mg2+ and Al3+ ions inside zirconia lattice structure. The outcomes indicate that MMA has significantly improved both the densification and stabilization behavior of m-ZrO2 through facilitating Y3+ diffusion inside zirconia lattice structure.