Growth mechanism of in situ MgSiN2 and its synergistic effect on the properties of MgO–C refractories

Abstract To improve the thermal shock resistance of MgO–C refractories, a novel MgO–C refractory, based on high-temperature nitriding, was prepared by introducing Si powder/phenolic resin loaded with catalyst into MgO–C refractories to form silicon-containing ceramic bonding phases in situ. The effects of catalyst content and nitriding temperature on the phase evolution, microstructure, mechanical properties, and corrosion resistance of refractories were investigated. The addition of catalyst accelerated the in-situ formation of more ceramic bonding phases as compared to the catalyst-free refractory, especially the influence on the morphology and quantity of MgSiN2, which determined the properties of MgO–C refractories. Here, the formation mechanism and morphological evolution of MgSiN2 in refractories were explored. In addition, the addition of 1 wt% ferric nitrate greatly optimized the microstructure of MgO–C refractories, and the sample showed excellent mechanical properties, thermal shock resistance, and corrosion resistance after nitriding at 1400°C.