Preparation of AlON ceramics via reactive spark plasma sintering

Al ₂O ₃ and AlN powder mixtures were used to synthesise AlON ceramics using the reactive spark plasma sintering (SPS) method at temperatures between 1400 and 1650°C for 15-45min at 40MPa under N ₂ gas flow. AlON phase formation was initiated in the samples sintered above 1430°C, according to the X-ray analysis. The complete transformation of the initial phases (Al ₂O ₃ and AlN) into AlON was observed in the samples that were spark plasma sintered at 1650°C for 30min at 40MPa. A high spark plasma sintering temperature together with a low heating rate produced a greater amount of AlON formation at a constant process time. The densification, microstructure and mechanical properties of the produced ceramics were analysed. The highest hardness value was recorded to be 16.7GPa, and the fracture toughness of the sample with the highest AlON ratio was measured to be 3.95MPam ^1/2.