Corrosion mechanisms of CaO to MgAl2O4 materials and ZrO2-MgAl2O4 materials
This work aims to study the corrosion mechanisms of CaO to MgAl2O4 materials and ZrO2·MgAl2O4 materials.MgAl2O4 micropowder,desilicated zirconia micropowder,and analytically pure cal-cium carbonate were used as raw materials.CaO micropowder was obtained by calcining the calcium car-bonate and crushing,and then the MgAl2O4 material was prepared with the mass ratio of MgAl2O4 micropow-der to CaO micropowder of 4∶1 and the ZrO2-MgAl2O4 material was prepared with the mass ratio of desilicat-ed zirconium powder,MgAl2O4 micropowder and CaO micropowder of 3∶4∶1.Both the materials were heat trea-ted at 1 500,1 600 and 1 700 ℃ for 3 h,respectively.The possible reactions in the system were analyzed using phase diagrams and thermodynamic calculations.The phase composition and microstructure of the fired sam-ples were analyzed by XRD and SEM.The results show that:for the MgAl2O4 material,CaO reacts with MgAl2O4 to form low-melting-point CaO·Al2O3 and 12CaO·7Al2O3;for the ZrO2-MgAl2O4 material,a large amount of CaO reacts with ZrO2 to generate high-melting-point c-ZrO2 and CaZrO3,while the remaining small amount of CaO reacts with MgAl2O4 to form CaO·Al2O3,which reduces the formation of low-melting-point phases.
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