Influence of Er2O3 content on microstructure and mechanical properties of ZTA-TiO2 composites

The influence of Er2O3 addition on the phase evolution and mechanical properties of sintered (1600 degrees C, 4 h) ZTA (yttria stabilized zirconia toughened alumina)-TiO2 composites was investigated. The SEM and XRD results reveal the formation of a new erbium zirconium oxide, Zr3Er4O12, with a granulate morphology when Er2O3 content is higher than 1 wt%. The grain sizes of both Al2O3 and yttria-stabilized zirconia phases decrease with an increase in the Er2O3 content. The relative density, Vickers hardness and fracture toughness of the composites are found to be strongly dependent on their grain sizes, relative densities and the formation of the Zr3Er4O12 secondary phases. The composite with 5 wt% Er2O3 shows the highest relative density (99.93%), Vickers hardness (1752 HV) and fracture toughness (7.92 MPa.m(1/2)). (C) 2019 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.