Silicon Aluminum Oxynitride/Corundum/Graphite/BN Omposite Refractories

The development of new steel-making such as clean steel making, ladle refining process and continuous casting techniques put forward to the life of refractories according to the automation and rationalization of smelting. The slide gate as a functional refractory with security, reliability and high efficiency plays an important role in continuous casting process to increase the ratio of the continuous casting and efficiency and decrease the cost of production. In recent decades, the refractories such as silicon nitride bonded silicon carbide, Sialon bonded silicon carbide and Sialon bonded corundum strut their stuff in the industry of iron and steel, and it shows nitrogen ceramics will have a promising prospective in the field of refractory.It is well known that the nitrides have high thermal coefficient and low thermal expansion coefficient, high toughness and non-wettability to oxide slag compared to oxides. So it can improve the thermal shock resistance and high temperature mechanical properties and slag erosion and penetration resistance. New type slide gate refractories will be prepared by introducing p-Sialon and AIN-polytypoids via in-situ reaction in a flowing nitrogen atmosphere. In this paper what have been done are given as follows:The first part focuses on the sintering properties and reaction mechanism of β-Sialon/Al2O3/graphite/BN composites materials prepared by in-situ nitriding process using Al, Si metal powders, -Al2O3 reactive powder in a flowing nitrogen at 1400 C-1600 C. The microstructure and phase composition are investigated, and its reaction mechanism is discussed thermodynamically.The second part focuses on the sintering properties and reaction mechanism of AlN-polytypoids/Al2O3 composites prepared by nitriding and aluminothermic reduction using Al, SiO2 ultrafine powder, -Al2O3 reactive powder in a flowing nitrogen at 1400 C-1600 C, The microstructure and phase composition are investigated, and its reaction mechanism is discussed thermodynamically.The third part focuses on the sintering properties and reaction mechanism of AlN-polytypoids/Al2O3/graphite/BN composites materials prepared by nitriding and aluminothermic reduction in a flowing nitrogen at 1400 C-1600 C, The microstructure and phase composition are investigated, and its reaction mechanism is discussed thermodynamically.The final part focuses on the sintering properties, room and high temperature mechanical properties of AlN polytypoids/Al2O3/graphite/BN composites and the molten iron resistance in air and coke bed.