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Abstract: This paper investigates the effects of AlPO4 addition on the corrosion resistance of andalusite LCC refractories. Corrosion tests using the Alcoa cup test (850°C and 1160°C for 150h and 72h, respectively) were conducted to determine the extent of penetration. The addition of AlPO4 was shown to improve the corrosion resistance of the castables in contact with molten Al-alloy. SEM/EDS analyses of the interfacial reaction zone showed the formation of corundum in the interfacial layer, along with a significant decrease in the phosphorus content in the interface. Thermodynamic calculations revealed that reaction with the alloy leads to the formation of corundum as the reaction product along with gaseous products (phosphorus trioxide gas) and small amounts of aluminum phosphide. Corundum formation at the interface enhances the corrosion resistance of sample due to high stability of corundum against molten Al alloy, while the metal quality is enhanced due to absence of dissolved phosphorus in the metal. [Copyright &y& Elsevier]

Abstract: Interfacial reactions between Al-alloy and andalusite low-cement castables (LCC) containing 5wt% V2O5 were analyzed at 850°C and 1160°C using the Alcoa cup test. Interfacial reaction products and phases formed during heat treatment of the refractory samples were characterized using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analysis. V2O5 addition resulted in the formation of glassy phases, which significantly improved the corrosion resistance. These phases were preferentially corroded by the alloy, due to their glassy nature. However, vanadium formed from reduction, formed intermetallic alloys (V–Al–Si–Mg), which formed an interfacial physical barrier to further alloy penetration. [Copyright &y& Elsevier]