Properties of multiple rare earth oxides co-stabilized YDyGdSmNd-TZP ceramics

Abstract

TZP starting powders containing 0.6 mol% each of yttria, dysprosia, gadolinia, samaria and neodymia stabilizer were fabricated by a wet chemical route by coating monoclinic zirconia with rare earth nitrates and subsequent calcination. The powders were consolidated by hot pressing in the temperature range between 1250 °C–1500 °C for 1 h at 60 MPa pressure. The materials were characterized with respect to microstructure, phase composition and mechanical properties. The materials combine high fracture toughness over the whole sintering temperature range with moderate hardness and attractive strength. XRD showed that a redistribution of stabilizers takes place during sintering, an initial highly tetragonal phase containing little or no stabilizer is successively eliminated and a stabilizer saturated tetragonal phase is progressively formed. The volume fraction of cubic increases with sintering temperature as the stabilizer content increases. Above 1500 °C, a plate-shaped aluminate phase is formed from the alumina sintering aid and rare earth oxide.