An Investigation of the effect of various metal oxides on sinterability and grain groth of 8 mol% yitria-stabilized cubic zirconia

AN INVESTIGATION OF THE EFFECT OF VARIOUS METAL OXIDES ON SINTEREBILITY AND GRAIN GROWTH OF 8 MOL % YITRIA-STABILIZED CUBIC ZIRCONIA (ML Sc Thesis) Bülent AKTAŞ GAZt UNIVERSITY MSTUTE OF SCINCE AND TECHNOLOGY December 2002 ABSTRACT In this study, the effect of various metal oxides on sinterebility and grain growth behaviour of 8 mol % yitria-stabilked cubic rirconia (8Y-CSZ) was investigated. For these purposes, lwt% ©-ALOs and SİO2 were selected as a dopant and doped with 8Y-CSZ by sip casting method, X Ray Difraction results showed that a-ALO* and SİO2 had very limited solubility of 0,3 wt % into 8Y-CSZ. The slip cast specimens were sintered at different temperatures and than annealed at 1300 °C and 1400 °C for 10, 30, 66,5 hours. It was seen that grain growth rates could be controlled by the deliberate addition of 1 wt % grain boundary phases of cs-ALOs and SiOz. A grain growth exponent of 3 and activation energy for grain growth of 298 kj/mol were obtained for undoped 8Y-CSZ. The CI-ALO3 containing samples had a grain growth exponent of 4 and activation energy of 361 kj/mol. The most effective intergranular phase for limiting grain growth was the low solubility SİO2 phase with a grain growth exponent of 4 and an activation energy of 382 kj/mol The slow grain growth in doped 8Y-CSZ is attributed to solute ions segregation in grain boundary region. The addition of the grain boundary phase results in limiting matter transfer along the grain boundary resulting in slower grain growth. Science Code Keywords Page Number Adviser 225.01.01 Zirconia, Slip Casting, Sinterebility, Grain Growth 97 Assoc. Prof. Dr. Süleyman TEKELİ