Effects of rare-earth oxides on the microstructure and mechanical properties of Al2TiO5 flexible ceramics

Abstract

In this work, aluminum titanate (Al2TiO5, AT) flexible ceramics modified with rare-earth oxides (La2O3 and Y2O3) were successfully prepared by solid state reaction sintering at 1400 °C in air for 2 h. To explore the effects of La2O3 and Y2O3 on the microstructure and mechanical properties of AT flexible ceramics, the phase compositions of the modified AT flexible ceramics was analyzed using X-ray diffraction (XRD), and the microstructure and crack propagation were analyzed by scanning electron microscopy (SEM). In addition, the grain size and oriented arrangement degree of the AT grains were determined by using Image J. LaTi2Al9O19 (LTA) and Y2Ti2O7 (YT) were generated after adding La2O3 and Y2O3, respectively. These second-phase grains were pinned at the grain boundaries of AT grains, strengthening the branch and deflection phenomena, and increasing the resistance to crack propagation during the bending test. Moreover, the presence of second phase grains hindered the growth of AT grains, resulting in a decrease in the grain size and degree of oriented arrangement. For these two reasons, the flexural strength of La2O3/Y2O3-modified AT flexible ceramics was significantly improved. Y2O3-modified AT ceramics produced with 3 wt.% Y2O3 presented a significant improvement (approximately 152%) in flexural strength relative to the pure AT ceramics.