Characteristics Of Thermal Oxidation On Hot-Pressed Pure Yttria Ceramics

We investigated the characteristics of hot- pressed pure yttria ceramics, and annealed them in an oxidation atmosphere. Regardless of the heat treatment in the oxidation atmosphere, XRD analysis showed that all the samples had a Y2O3 phase without structural change. Even though the color variation of the hot- pressed Y2O3 ceramics was due to the sintering temperatures, the oxidation process turned the color of the Y2O3 ceramics into white. The color change during oxidation treatment appears to be related to oxygen defects. In addition, oxygen defects also affected the weight change and microstructure of the Y2O3 ceramics. The Y2O3 ceramic sintered at 1600 degrees C had a 5.03 g/cm(3) density, which is close to the theoretical density of Y2O3. As the sintering temperature increased, small homogeneous grains grew to large grains which affected the Vickers hardness. Y2O3 ceramics hot- pressed at 1600 degrees C and annealed at 1200 degrees C had a flexural strength of 140MPa.