PHASE EQUILIBRIA IN THE Al2O3–TiO2–Y(Er)2O3 SYSTEMS AT 1400 ºС

Abstract

The aim of this investigation is the construction of isothermal sections for the Al2O3-TiO2-Y(Gd)2O3 phase diagrams at 1400ºС as part of systematic investigations of Al2O3-TiO2-Ln2O3 (Ln=lanthanides, Y) systems. The 1400°C was taken as the temperature, at which no liquid phases are expected in the both systems. The isothermal sections at 1400 °С for the Al2O3– TiO2–Y(Er)2O3 phase diagrams were constructed for the first time. Samples were prepared by a chemical method. Samples were annealed in air at 1400°С for 80 hours and cooled in the furnace. This temperature value was selected with a view to provide possibility of phase transformations character studies. New phases and appreciable solubility regions based on the components and binary compounds were not found, as predicted. Triangulation of the systems is determined by the phase Y(Er)2T2O7, which is in equilibria with compounds Al2TiO5, Y(Er)3Al5O12, Y(Er)AlO3, Y(Er)4Al2O9 and components TiO2 and Al2O3. The structures of isothermal sections of the both systems are similar. The systems are triangulated into six secondary triangles, in which three-phase eutectic are expected. In five quasibinary sections two-phase eutectic should expect to exist. The obtained results will make a significant contribution to the understanding of interactions between the components in the systems studied.This systems offer a number of promising opportunities such as high-temperature structural composites based on directionally solidified two-phase and three-phase eutectic materials, solid electrolytes (SOFCs, oxygen sensors, film for electronic devices, etc.), promising to accumulate water, immobilizing materials for nuclear industry, tough ceramics, catalysts carriers, wear- and corrosion-resistant ceramic coatings and super refractories.

Keywords

• керамічні матеріали, фазові рівноваги, ізотермічні перерізи, діаграми стану