Analysis of the Corrosion Mechanism of MgO-C Bricks by Calcium Aluminates Slags with low Content of Reducible Oxides

摘要

The dynamic corrosion test allowed identifying the main chemical wear mechanisms of MgO-C bricks of steel ladle slag line by calcium aluminate slags with low content of reducible oxides. Additionally the slag of highest content of FeO + MnO result the most aggressive for the refractory. The composition and characteristics of the slags determine the corrosion mechanisms of the MgO-C: centre dot Accentuated decarburation of the matrix with FeO + MnO slag contents greater than 4 percent. centre dot Slag penetration. centre dot MgO grain corrosion by the action of the alumina and calcium oxide. centre dot Loosening of MgO grains. Slag with FeO + MnO contents higher than 4 percent , promote the brick wear, being the main wear mechanism the matrix decarburation. These slag, although being saturated in MgO (contents of solid phase smaller than 30 percent) do not prevent the wear of the refractory material. Slag with low FeO + MnO content (less than 4 percent) and variable alumina content contribute to reduce the brick wear by the chemical adherence of it. Liquid slag promotes the penetration in the interior of the brick, being the main mechanism attack the chemical corrosion by the action of the alumina (calcium and magnesium aluminates of low temperature of first formation of liquid phase). As future tasks, the results obtained in the present work will be validated at industrial scales and the evaluation of the corrosion mechanisms of MgO-C bricks at laboratory scale using slags with different contents of Al_2O_3 and MgO keeping constant the FeO + MnO content in 4 percent will be performed.