2016 Volume 56 Issue 2 Pages 189-194
To study the substitution of Fe3Si–Si3N4 for refractories in the upper RH refiner, this paper simulated the service condition of RH refining and studied the change of the Fe3Si–Si3N4 in the simulated condition. A Fe3Si–Si3N4 specimen prepared by flash combustion was put in a vacuum sintering furnace with carbon lining, fired at 1450°C under 80 Pa of vacuum degree for 2 h, and then cooled. The morphological evolution before and after being treated and phase interactions of the Fe3Si–Si3N4 specimen were studied and analyzed thermodynamically and dynamically. The results show that at high temperatures in vacuum, Fe volatilizes from the Fe3Si melt in Fe3Si–Si3N4 and reacts with Si3N4 on the Si3N4 crystal surface, forming new FexSi melt there; then Fe continues to volatilize from the new FexSi melt, causing FexSi alloy particles finer and more uniform in Fe3Si–Si3N4; the hexagonal columnar Si3N4 crystals begin to decompose partially, and become cylindrical with edges and corners disappearing; during prebaking or operation interval of RH refining, a SiO2 film which has better stability than Si3N4 is developed on the surface of Si3N4 crystals or Fe3Si–Si3N4 bricks, preventing the decomposition of Si3N4 and improving the application feasibility of Fe3Si–Si3N4 in RH refining.