Pressureless sintering of machinable Al2O3/LaPO4 composites in N2 atmosphere

Al2O3/LaPO4 composites were fabricated by pressureless sintering in N2 atmosphere. The effect of sintering temperature and sintering time on densification was examined, as well as the dependence of mechanical properties and microstructure on LaPO4 content. Provided the ratio of La/P was close to 1:1, no reactions were observed after 2 h at 1650 °C in N2 atmosphere. The 30 wt.% LaPO4/Al2O3 composites could be machined using cemented carbide drills as those pressureless sintered in air. LaAl11O18 was formed when the composite was sintered at 1700 °C for 1 h in N2 atmosphere, and the composites were not machinable.