In situ synthesis mechanism of 15R–SiAlON reinforced Al2O3 refractories by Fe–Si liquid phase sintering

15R–SiAlON bonded Al2O3 refractories were successfully synthesized using ferrosilicon nitride and alumina by liquid phase sintering. The phase composition and morphology were analyzed by means of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show that 15R–SiAlON reinforcement can be in situ obtained in the specimens with 5 wt% ferrosilicon nitride at 1500°C to 1700°C in flowing N2 of 0.1 MPa. The morphology of 15R–SiAlON is strongly dependent on the morphology of intermediate AlON phases formed at different temperatures. Fe–Si alloys from ferrosilicon nitride form liquid phase and accelerate the formation of 15R‐SiAlON, in which process the wettability of Fe–Si alloys is improved by the increase in Si content, carbon coating on particle, solution process and reactions. The 15R–SiAlON reinforced Al2O3 refractory materials possess high cold crushing strength of 138‐171 MPa.