The phase evolution of resin‐bonded Al ₂ O ₃ ‐Al refractory containing magnesia under N ₂ ‐blowing

Abstract Phenolic resin‐bonded Al ₂ O ₃ ‐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‐Al ₂ O ₃ , spinel solid solution (MgAlON), Al ₄ O ₄ C, Al ₄ C ₃ and unreacted aluminum. The phases after heating at 1600°C were α‐Al ₂ O ₃ , spinel solid solution (MgAlON), Al ₄ O ₄ C, Al ₄ C ₃ , (Al ₂ OC) _x (AlN) _1‐x solid solution, Al ₈ O ₃ N ₆ , 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, Al ₂ O ₃ , Al, and N ₂ at 1300°C. With sufficient magnesia, the stability of Al ₄ O ₄ C and Al ₄ C ₃ 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 Al ₂ O ₃ ‐Al composite under a nitrogen atmosphere, more stabilized MgAlON was formed.