AlON ceramics were prepared by one-step aluminothermic reduction and nitridation method using micron-sized Al and nanoscale γ-Al2O3 powders as the starting materials. The results showed the optimal Al content for single-phase AlON preparation was 11 wt%. At the temperature below 1650℃, AlN was primarily produced by direct Al nitridation. Then AlN reacted with Al2O3 forming AlON at above 1650℃. Single-phase AlON was synthesized at 1700℃, but the sintering among AlON particles was barely observed, which only occurred at higher temperature. For samples calcined at low temperature (≤1700℃), the phase compositions of both interiors and exteriors were basically the same. However, the interiors maintained pure AlON while the exteriors were over nitrided and AlN impurity appeared at high temperature (≥1750℃). Such phenomenon was analyzed with emphasis of thermodynamics.
