Chrome-Free Low Solar Absorbance Single Coat for Aluminum Alloys

Superstructures and freeboards on aluminum ships require both corrosion protection from the marine environment and solar absorption resistance to keep ship interiors cool. Traditional coating stack-ups that include surface pretreatment with conversion coatings to protect the aluminum substrate from corrosion have unrealistic application procedures for these structures. Moreover, hexavalent chromates used in both anodization and conversion coatings are highly toxic to Navy personnel and the environment. While a low solar absorbance (LSA) topcoat would reduce the energy load to keep these structures cool, its weight adds significant costs to ship operation. There is a need for a chrome-free and low solar absorbance coating that is easily applied onto nominally prepared uncoated aluminum surfaces and cured to a minimal film thickness. Luna Innovations Incorporated proposes a single component paint-like coating designed for direct-to-metal application to meet these needs. Luna will utilize nonchrome corrosion inhibitors with tuned activity for long-term corrosion protection, and will incorporate anti-staining additives to help the coating maintain a grey oxide finish.