Colloidal processing and partial sintering of high-performance porous zirconia nanoceramics with hierarchical heterogeneities

High-performance, porous, Y-TZP nanoceramics with hierarchical heterogeneities originating from uniform, intra- and inter-particle packing were prepared by colloidal processing and partial sintering of a mesoporous powder. The powder consisted of 100-150-nanometer-sized secondary particles initially composed of smaller, loosely aggregated, primary, nanoscale crystallites. Green bodies were prepared by centrifugal slip casting of weakly flocculated suspensions. During the initial stage of sintering, necking between the secondary particles was accompanied by intra-particle pore coalescence, while the pores originating from the secondary particle packing remained intact. Such microstructures with porosity levels between 46 and 18.3% and pore areas between 18 and 4 m2/g led to attractive properties, i.e., much reduced thermal conductivities of 0.63-1.88 W m−1 K−1, high bending strengths of 70-540 MPa and lowered elastic moduli of 32-156 GPa, making them potentially ideal as thermal insulators and/or load-bearing porous biomaterials owing to the possibility of further impregnation with bioactive ingredients.