A novel strategy for the fabrication of AlN–AlON refractories: Nitrogen gas pressure sintering of Al 4 O 4 C

A novel strategy was exploited for the fabrication of AlN–AlON refractories via nitrogen gas pressure sintering of Al 4 O 4 C. The phase transformation and microstructure evolution during the reaction at 1600–1800°C were thoroughly investigated. The results indicated that the high N 2 pressure was essential for the effective nitridation. The in situ generated AlN–AlON refractories had a homogeneous local chemical composition, and the (101) plane of AlN and the (222) lattice plane of Al 5 O 6 N were bonded at their grain boundary with no amorphous phase. The as‐fabricated AlN–AlON refractories treated at 1700°C by a 20 atm nitrogen pressure exhibited an optimum bending strength of 111.10 MPa, combining an apparent porosity of 20% with a low bulk density of 1.97 g/cm 3 . The diffusion of the generated oxygen led to an increase in the apparent porosity and decrease in the bulk density at 1800°C. Furthermore, the fabrication mechanism of AlN–AlON refractories under the nitrogen gas‐pressure was discussed.