Typical corrosion of alumina refractory in aluminum reflow oven

The refractory linings of furnaces for secondary melting of aluminum, are exposed to intense attack by the molten metal. This occurs, because molten aluminum has a strong reducing power over the refractory oxide components, particularly Fe₂O₃, SiO₂ and TiO₂. In this work, based on X-ray diffraction and scanning electron microscopy, it is presented a post mortem study of the mechanisms that lead to a premature wear of a 80% Al2O3 chemically bonded refractory bricks, used in the metal line of an aluminum re-melting furnace. The SEM analysis demonstrated that the oxides SiO₂ and TiO₂ contained in the refractory were reduced and transformed into their metallic elements causing an intense structural spalling. (author)