Effects of Y2O3 content on lattice parameters, sintering behaviour and mechanical properties of Al2O3/15 wt-%ZrO2 porous composite ceramics

The effects of different amounts of Y2O3 addition (0, 0.25, 0.50, 0.75 and 1.00 wt-%) on the lattice parameters, sintering behaviour and mechanical properties of Al2O3/15 wt-% ZrO2 porous composite ceramics have been investigated. It is found that Y2O3 and Al2O3 tend to form Al5Y3O12 rather than a solid solution of (Al1-XYX)(2)O-3, while Y3+ can displace Zr4+ of ZrO2 to form a solid solution and increase the lattice constants of tetragonal zirconia (t-ZrO2). The additions of Y2O3 into Al2O3/15 wt-% ZrO2 porous composite ceramics not only stabilise t-ZrO2 but also act as a sintering aid for promoting the sintering process. In addition, Y2O3 additions are beneficial to improving the modulus of rupture and cold crushing strength of Al2O3/15 wt-% ZrO2 porous composite ceramics; their maximum values are obtained at 0.75 wt-% Y2O3, which are 56 and 118 MPa respectively.