Evolution mechanism of MgAlON in the Al-Al2O3-MgO composite at 1800 degrees C in flowing nitrogen

摘要

The Al-Al2O3-MgO composite was calcined at 1800 degrees C in flowing nitrogen, using fused corundum, tabular alumina, activated alpha-Al2O3, high purity magnesia and metal aluminum powder as raw materials and magnesium aluminate sol as binding agent. The calcined sample was characterized and analyzed by XRD, SEM and EDS, and evolution mechanism of MgAlON was studied. Formation mechanism of MgAlON can be described as follows. At elevated temperatures in flowing nitrogen, Al(g)/Al2O(g) diffuses and transfers along pores or gaps in the Al-Al2O3-MgO composite, being nitrided as AlN, and then AlN reacts with Al2O3-rich spinel to form granular MgAlON. In gas-gas reaction system, Al(g)/Al2O(g), N-2(g), Mg(g) and O-2(g) react to form flake MgAlON.