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.