Effect of ZrO2 addition on the mechanical properties of porous TiO2 bone scaffolds.

This study aimed at the investigation of the effect of zirconium dioxide (ZrO2) addition on the mechanical properties of titanium dioxide (TiO2) bone scaffolds. The highly biocompatible TiO2 has been identified as a promising material for bone scaffolds, whereas the more bioinert ZrO2 is known for its excellent mechanical properties. Ultra-porous TiO2 scaffolds (>89% porosity) were produced using polymer sponge replication with 0-40 wt.% of the TiO2 raw material substituted with ZrO2. Microstructure, chemical composition, and pore architectural features of the prepared ceramic foams were characterised and related to their mechanical strength. Addition of 1 wt.% of ZrO2 led to 16% increase in the mean compressive strength without significant changes in the pore architectural parameters of TiO2 scaffolds. Further ZrO2 additions resulted in reduction of compressive strength in comparison to containing no ZrO2. The appearance of zirconium titanate (ZrTiO4) phase was found to hinder the densification of the ceramic material during sintering resulting in poor intergranular connections and thus significantly reducing the compressive strength of the highly porous ceramic foam scaffolds.