Fracture mode and compressive strength of ice-templated porous zirconia

Abstract Porous zirconia with different porosity and pore architecture were prepared by adjusting the solid loading and the binder concentration of the suspensions via an ice-templating method. The transition of the fracture mode and the relationship between the compressive strength and process parameters were identified and investigated. The load-displacement curves showed a variation from a buckling fracture at porosity above 70 % to a brittle fracture in the porosity range from 35.3 % to 55.5 %, owning to the increased resistance of the ceramic walls to buckling. As the porosity decreased from 75.0 % to 35.3 %, the mean compressive strength of the samples increased from 4.5 MPa to 197.1 MPa. Under buckling fracture, increasing the binder concentration from 2wt% to 4wt% contributed to the improvement of the mean compressive strength from 5.5 MPa to 14.8 MPa, although samples had similar porosity level (∼73 %). For brittle fracture, samples with porosity around 54 % exhibited the improvement of mean compressive strength from 45.5 MPa to 75.1 MPa when increasing the freeze velocity from 8 °C/min to 25 °C/min.