Surface modification of 3Y-TZP with cerium oxide

Surface modification with cerium oxide of tetragonal zirconia polycrystals stabilized with 3 mol.% yttria (3Y-TZP) was carried out in order to improve the resistance to low temperature degradation. Specimens were coated with pressed CeO₂ powder and then annealed at 1400 °C and 1500 °C for periods of up to 10 h. Similar treatments were performed in specimens coated with a sub-micron CeO₂ layer by means of magnetron sputtering. Cerium penetration in the surface modified specimens is about 10 μm into the bulk and the grain size increases in the surface layer affected by cerium diffusion. The indentation bulk fracture toughness and Vickers hardness are not affected by the surface modification treatments. Berkovich nanoindentation was performed to observe the contact hardness and elastic modulus at the surface, showing no significant difference after surface modification. Surface modification with ceria induces a large increase in the resistance to hydrothermal ageing without impairing mechanical properties.