Effect of chemical composition and morphology of zirconia particles on properties of HAp-zirconia particulate composites

Isometric or needle-shaped particles of non-stabilised zirconia or zirconia stabilised with CaO or Y2O3 were incorporated into a hydroxyapatite (HAp) matrix. The HAp powder was prepared by a precipitation method. A co-precipitation method followed by calcination or hydrothermal treatment was used to manufacture zirconia powders of isometric or needle-shaped morphology, respectively. Precipitation of amorphous calcium phosphates was performed directly on surface of zirconia crystallites. Mixtures containing 11.9 vol. % of zirconia particles in the HAp matrix were prepared. The composite powders were hot pressed for 0.5 h at temperatures 1150-1250 degreesC under 25 MPa in an argon atmosphere. A strong dependence of sinterability of the composite powders and mechanical properties of the resultant composites on chemical composition and morphology of the zirconia powders was found. A significant improvement of mechanical properties of HAp - zirconia composites when compared to the mono-phase HAp ceramics has been found especially, in the case of application of the non-stabilised zirconia powder.