Effect Of Matrix Regulation On Alumina-magnesia Refractory Dry Mix For Induction Furnace

Intermediate frequency induction furnaces are widely used in precision casting and smelting tool steels,alloy steels,high manganese steels and special steels due to their diverse smelting steel types,environmental protection and high efficiency.Due to the harsh use conditions,the life of the induction furnace lining is low,and the production cost is increased,which severely limits the development of Chinese metallurgical and foundry industries.Therefore,the development of cheap and long-life furnace lining materials is imminent.In this paper,fused white alumina and fused magnesia are used as the main raw materials.The matrix of alumina-magnesia refractory dry mix is regulated by the addition of alumina micro-powder,pre-synthesized spinel and rare earth oxides to control the spinel reaction expansion and improve material properties.research shows:?1?Alumina micro-powder can improve the cold crushing strength of materials at different heating treatment temperatures,and consider the introduction of 5wt%alumina micro-powder.?2?Al₂O₃/MgO ratios of alumina-magnesia refractory dry mix's matrix with different substrates have no obvious difference in line change rate and the cold crushing strength.Compared with the matrix Al₂O₃/MgO molar ratio of 1.2,spinel crystals are small and uniform at high temperatures.The spinel's grains of which molar ratio is 0.8 are coarse.?3?The addition of 7wt%pre-synthesized spinel can control the expansion of alumina-magnesia refractory dry mix and enhance the structural strength.After heating at1600?,the CCS of the material increased from 6.8MPa to 12.7MPa.Different types of spinel have different reaction characteristics.Magnisia rich pre-synthesized spinel MR66reacts with corundum to form loose spinel around the spinel particles;alumina rich pre-synthesized spinel AR90 reacts with the periclase and forms a dense spinel transition layer.?4?Adding Y₂O₃ and La₂O₃ can reduce the linear change of the material,improve the CCS and HMOR.YAG-MA double-phase structure enhancement by the addition of Y₂O₃,and promotes densification of the material.The addition of lanthanum oxide reacts to produce flaky LaAl₁₁O₁₈ or hexagonal flaky LaMgAl₁₁O₁₉,which enhances the bonding strength between the material's matrix and aggregates.The HMOR of material with 0.5wt%Y₂O₃ or 0.25wt%La₂O₃ increased 180%and 40%.?5?The appropriate addition of pre-synthesized spinel,Y₂O₃ and La₂O₃ can improve the comprehensive properties of the material.The addition of 0.5wt%Y₂O₃ and 0.25wt%La₂O₃ are better than the addition of 7wt%pre-synthesized spinel for improving the high temperature strength and resistance to slag erosion of materials.Under free expansion or restraint conditions,the addition of pre-synthesized spinel,Y₂O₃ and La₂O₃ has significantly improved the slag penetration resistance of the material.