关键词: 超低碳钢冶炼, MgAlON复相材料, 用后滑板砖, 抗弯强度, 抗钢液侵蚀性

Abstract: To promote the chromium-free smelting of ultra-low carbon steel and high value-added utilization of spent refractories,MgAlON composites were in-situ synthesized by the carbothermal reduction nitriding method with spent slide bricks,spent MgO-C bricks and Al₂O₃ micropowder as raw materials through pressureless sintering at 1 600 ℃ for 3 h.The effects of the spent slide brick additions (0,22.22%,44.44% and 66.66%,by mass) on the phase composition,morphology and properties of the specimens were investigated.The molten steel corrosion resistance of some specimens was investigated as well.The results show that: the principal crystalline phase of all the specimens is MgAlON.With the spent slide brick addition increasing,Al₂O₃ in the specimens disappears,the amount of β-SiAlON and ZrN gradually increases,the internal porosity of the material decreases first and then increases,and the bulk density and bending strength increase first and then decrease;meanwhile,the fracture mode of the specimens changes from transgranular fracture to transgranular fracture with a small amount of intergranular fracture,and finally to cleavage fracture.When the spent slide brick addition is 44.44%,the specimen has the best comprehensive performance with the bending strength of 140.1 MPa,corrosion depth of 76 μm after corrosion in molten ultra-low carbon steel at 1 600 ℃ for 2 h and the utilization rate of the spent bricks of 55.56 mass%.

Key words: ultra-low carbon steel smelting, MgAlON composites, spent slide bricks, bending strength, molten steel corrosion resistance