Cerium, Cobalt and Molybdate Cation Storage States, Release and Corrosion Inhibition when delivered from on Al-Transition Metal-Rare Earth Metal Alloys

Aluminum and aluminum alloys can be protected against corrosion by various methods of surface modification (e.g., metal finishing, anodizing, chromate conversion coatings, metallic cladding with Alclad, corrosion protection compounds, and solution phase inhibitors). The desire to deploy environmentally compliant multi-functional coatings has created the need for new concepts that can protect Al-base precipitation age hardened alloys. A new generation of aluminum alloys with certain transition metals or lanthanides in an amorphous state provides an opportunity to create an environmentally compliant metal coating with multiple functions. Such metallic coatings not only can improve the resistance to localized corrosion, but also have the potential to provide a means for active corrosion protection at coating defects that expose underlying structural alloys (i.e., self-healing). The desired attributes of any new inhibitors (whether stored in a metal or polymer coating) are high capacity in the coating, high solubility in the aqueous phase over the coating when released, and high inhibiting efficiency. If such novel alloys are successful, the opportunity exists to create new multi-functional metallic cladding alloys that exhibit a broad range of corrosion functions. One aspect of this MURI project involves the exploration of Al-based metallic glasses for coatings (metallic cladding) and the testing of different alloy compositions that could add functions ranging from improvement of corrosion barrier properties to sacrificial cathodic protection. Various cladding alloy compositions such as [Al-TR (Mo, Co, Ni, Fe, Cr) RE (Ce, Gd, Y), Al-Cu-Mg-Ni (Ni promotes solid solubility of Cu and Mg) or Al-Sn (Sn promotes properties suitable for sacrificial anode applications)] are possibilities. The overall goal is to synthesize alloys with targeted composition to produce the desirable attributes and properties that achieve each function.