Influence of ceramic phase content and its morphology on mechanical properties of MgO–C refractories under high temperature nitriding

Abstract

To evaluate the influences of ceramic phase content and its morphology on the mechanical properties of MgO–C refractories, pre-prepared Si powder-phenolic resin loaded with Fe2O3 was introduced to prepare MgO–C refractories via catalytic nitridation. The effects of nitriding temperature and Fe2O3 content on the phase composition, microstructure evolution and properties of MgO–C refractories were studied and compared. The results show that the increase of the nitriding temperature was conducive to the in-situ formation of the ceramic phases, and a new phase of Mg2SiO4 was formed at temperatures ≥1450 °C. Both the increase in nitriding temperature and the addition of catalyst could inhibit the growth of α-Si3N4 to promote the formation of β-Si3N4 and MgSiN2. In addition, the formation of excessive ceramic phases caused samples after nitriding to expand violently and form more porous, thereby reducing the physical properties of MgO–C refractories.