In-situ sintering reaction of Al2O3-LaAl11O18-ZrO2 composite

Al2O3-LaAl11O18-ZrO2 composites were prepared by in situ sintering reaction of different proportions of Al2O3 and La2Zr2O7. The studied batches were uniaxially pressed and pressureless sintered at 1600 °C up to 1725 °C for 1 h. Phase composition study reveals that the only present phases are alumina, lanthanum hexaluminates and zirconia. No other intermediate phases are present. Rodlike LaAl11O18 was observed in the sintered bodies containing more than 25 wt.% LaAl11O18. The effect of rodlike particles on the densification and mechanical behavior was discussed. It was found that increasing the LaAl11O18 content more than 25 wt.% enhances the fracture toughness, but reduces both the bending strength and the hardness of the sintered composites.