Theoretical Model of Hardening in Zirconia−Nickel Nanoparticle Composites

Well dispersed zirconia−nickel nanocomposites have been prepared by precipitation, reduction, and sinterization of nickel salts on zirconia powder. A notable increase of the hardness in samples with extremely low nickel content has been found. A hardening model based on the singular properties of nanocrystals and percolation theory has been proposed. The agreement between the experimental and the theoretical model is remarkably good and predicts a hardness of 40 GPa for Ni nanoparticles embedded into zirconia matrices.