Exploring Microstructure and Bending Strength of Al2O3 Ceramics Doped with Sm2O3 Rare-Earth Oxide: Impact of Volume Ratios and Sintering Temperatures

Abstract

The effects of low amounts (0, 0.1, 0.3, 0.5, 0.8, 1, 2vol%) of Sm2O3 on the densification, microstructure, and bending strength of Al2O3 were studied for different sintering temperatures. Sm2O3 and Al2O3 powders were mixed by ball milling, and Al2O3-Sm2O3 ceramics were prepared by dry and cold isostatic pressing in disc form before pressureless sintering at 1550°C and 1600°C/2 h in the air, separately. Sm2O3 reacted with Al2O3 by forming SmAlO3. The rod-like morphology of the SmAlO3 was generally achieved for 0.8 and 1vol% Sm2O3 for sintering at 1600°C, whereas the rod-like form was more obvious for the samples sintered at 1550°C. Similar relative densities were attained for all Sm2O3 ratios at both sintering temperatures, but the Al2O3 sintered at 1550°C exhibited higher densification than the Al2O3 sintered at 1600°C. The strength values were close, while a strength increase of about 5% was obtained for 0.5 vol% Sm2O3 containing ceramics sintered at 1600°C caused by the higher densification compared to the Al2O3. The strength showed a prominent drop above the ratio of 0.1 vol% Sm2O3 for sintering at 1550°C. The addition of present amounts of Sm2O3 did not have a significant effect on the mechanical properties of Al2O3 but it changed the microstructure.