| A new method for corundum corrosion test at 1200°C, which allows corroding refractory materials with the corundum that is usually formed on the walls of aluminium melting and holding furnaces has been developed. With this new method, it should be possible to select the most appropriate refractory lining for aluminum treatment furnaces, with much more confidence.;Through this new method, some new additives to increase the resistance of alumino-silicate refractories by molten Al-5%Mg-5%Zn alloys were developed. In order to understand the corrosion mechanism, XRD, mercury porosimetry and optical micrography were used as characterizing tools.;Four kinds of new additives were identified.;These involve the presence of boron or are made of AlPO4, alkaline earth oxides and rare earth oxide.;Addition of boron-based additives (BN, B4C, ZrB2, CaB6 and TiB2) favors the formation of B2O 3-Al2O3 crystalline phases.;Alkaline earth metal oxides and rare earth oxides can react with silica, and new crystalline phases such as anorthite (CaO·Al2O 3·2SiO2), barium anorthite (BaO·Al2O 3·2SiO2), and Y2O3·SiO 2 are formed. These transformations reduce the amount of free silica within the matrix of refractories. Refractory protection is achieved by these new crystalline phases, which prevent reaction between silica and aluminium metal. (Abstract shortened by UMI.). |
