Role of nano-Al2O3 particles in improving the properties of MgO–C slide plate materials

The unfired Al–Si incorporated MgO–C slide plate materials were manufactured using magnesia aggregates and fines, SiC aggregates, Al, Si and B4C powders as the raw materials, trace nano-Al2O3 particles as additive, and phenolic resin as binder. The contributions of nano-Al2O3 in the properties, phase composition and microstructure of MgO–C materials were studied. The reseult indicates that nano-Al2O3 is beneficial to improve mechanical properties of the materials, which is attributed to the good filling and pinning effects of nanoparticles. Highly reactive nano-Al2O3 can promote the densification of MgO–C materials and in-situ formation of ceramic phases at high temperatures, and a large number of non-oxide whiskers contributes to the formation of a continuous interlocking networks, which improves the high-temperature strength and TSR of MgO–C materials. Moreover, nano-Al2O3 promotes the formation of fine-grained pinel and forsterite protective layer in the high-temperature oxidizing atmosphere and prevents the diffusion of oxygen into the interior of the material, thus improving the oxidation resistance of MgO–C refractories.