In the automotive industry, aluminum alloys are of particular interests in providing the fuel economy needed to meet the required Corporate Average Fuel Economy (CAFE) standards. Current commercial cast aluminum alloys use Strontium (Sr) to modify the eutectic silicon morphology leading to improve ductility. However, the fading of Sr addition effect at the molten temperature remains as a major concern. Recently, it was demonstrated that the addition of nanostructured silanol based on polyhedral silsesquioxanes to cast aluminum alloys provided the refinement of eutectic silicon morphology without fading when held at molten temperature up to 96 hours. In addition, using master ingots containing nanostructured silanols, large-scale commercial alloys have been successfully modified.In this work, aluminum coated with nanostructured silanol of different chemical moieties were investigated. The contact angle measurement and powder sedimentation experiments have shown the increase in the hydrophobicity with nanostructured silanol coating. In addition, durability of the coating was also examined. Secondly, we investigated the electrochemical behavior of several casted aluminum alloys. The open circuit potential measurement and potentiodynamic polarization measurement show that the microstructure refinement with Sr or TSP will not affect the corrosion behavior on the hypo-eutectic Al-Si alloys but will reduce the anodic current density of the eutectic Al-Si alloys.
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