Corrosion Inhibiting Surface Treatment for Uncoated Marine-Grade Aluminum Alloys

Marine-grade aluminum alloys (5XXX-series) are increasingly being used in naval combatants because they have high strength and high corrosion resistance. In order to decrease weight, these corrosion resistant marine-grade aluminum alloys are not painted with the conventional primer and low solar absorbance topcoats. Although 5XXX series wrought aluminum alloys generally exhibit excellent corrosion resistance, exposure to moderately elevated temperature (which is unavoidable) can cause sensitization. Once sensitized the aluminum is susceptible to intergranular forms of corrosion including intergranular stress corrosion cracking (SCC). Stress corrosion cracking is particularly threatening because the stresses sufficient for crack initiation and crack growth can be far below the stresses required for normal gross failure. The goal of this SBIR project is to develop a new protective surface treatment for currently uncoated marine-grade aluminum alloys. TDA Research, Inc has developed novel corrosion inhibitors to mitigate stress corrosion cracking in senstizied Al5XXX series aluminum. In the Phase I project we demonstrated the feasibility using these corrosion inhibitors in a thin protective surface treatment. In the Phase II program we will optimize the surface treatment formulation so that it meets all Navy requirements and is ready to be qualified for military acquisition.