The Investigation On The Properities Of The Magnesia-alumina-titania Refractories And Corrosion Resistance To The Secondary Steel Refining Slags

The phase constitutions of magnesia-alumina-titania refractories were designed by the analysis of phase digrams and thermodynamic calculation, by which the the periclase and spinel solid solution (MgAl2O4-Mg2TiO4) were designed as the main crystalline phases, and the calcium titanate and forsterite with high melting point as the bonding phases.The properties and microstructure of magnesia-alumina-titania refractories were studied by means of experiment measurement and the microstrcuture analysis of SEM and EDAX. The influences of sintering temperature, titania content, alumina content on the properties and microstructure of magnesia-alumina-titania refractories were discussed. The results shows that: 1, The apparent porosity decreases and the bulk density increases with the increasing of sintering temperature.2, The apparent porosity decreases, the bulk density and the thermal shock resistance increases with the increasing of titania content. 3, With the increasing of alumina content, the bulk density generally increases, but the thermal shock resistance continuously increases. 4, The refractories have dense matrix and a little amount of pores. The main crystalline phases in the matrix are also the periclase and spinel solid solution, which are bonded by calcium titanate and forsterite with high melting point.The corrosions of the secondary steel refining slags on the refractories were studied by the method of stationary crucible, through which the corrosion mechanisms were discussed by the methods of measuring corroded area and microstructure analysis. The results shows that: l,The slag corrosion resistance of magnesia-alumina-titania refractories is comparable to that of magnesia-chromite refractories. But the slag resistance of magnesia-alumina-chromite-titanla refractories is prior to that of magnesia-alumina-titania refractories. 2, In the ranges involved, the slag corrosionresistance increases with the increasing of titania and alumina content. 3, The penetration of slags into the refractories is the main facts observed. The reaction of slags with the periclase of magnesia-alumina-titania refractories, results in the dissolving of periclase in the CaO-SiO2-Al2O3-MgO slags, and the penetration of slags into the refractories is enhanced by the formation of low melting silicates.