The phase evolution of resin‐bonded Al₂O₃‐Al refractory containing magnesia under N₂‐blowing

Abstract

Phenolic resin‐bonded Al2O3‐Al‐MgO refractories were prepared from sintered alumina and aluminum as raw materials, adding 3 wt%, 9 wt% and 15 wt% high‐purity magnesia. The green samples were treated at 200°C and heated at 1300°C and 1600°C in a nitrogen atmosphere. The results showed that the phases after heating at 1300°C were α‐Al2O3, spinel solid solution (MgAlON), Al4O4C, Al4C3 and unreacted aluminum. The phases after heating at 1600°C were α‐Al2O3, spinel solid solution (MgAlON), Al4O4C, Al4C3, (Al2OC)x(AlN)1‐x solid solution, Al8O3N6, and unreacted aluminum, with a tendency to shift from Al‐O‐C to MgAlON with increasing MgO content. MgAlON was obtained by in situ synthesis of MgO, Al2O3, Al, and N2 at 1300°C. With sufficient magnesia, the stability of Al4O4C and Al4C3 decreases at 1600°C, and AlON is formed with better stability and can be solubilized into MgAlON. That is, when magnesia was added to the phenolic resin‐bound Al2O3‐Al composite under a nitrogen atmosphere, more stabilized MgAlON was formed.