Inexpensive Non-Toxic Pigment Substitute for Chromium in Primer for Aluminum Substrate

One objective of the project is to identity non-polluting Li-based inhibitors for suppressing the corrosion of aluminum alloys to a degree that they will represent satisfactory substitutes for environmentally hazardous chromium coatings that are widely used. Since all corrosion involves oxidation and reduction it can be measured by observing the flow of electrons in a system. A device which does this is a 'Potentiostat.' If no current flows, corrosion is stopped. A series of non-carcinogenic and low toxicity lithium salts passivate aluminum and hence interrupt corrosion. A statistical series was set up to optimize the salts. A patent application is being prepared. A literature search has indicated that this is a new approach. Another concept which shows promise is to heat aluminum-lithium alloys (about 3% lithium) to 350 deg C for 30 minutes in argon gas. This relocates the lithium onto the surface of small (200 to 320 mesh) pigment particles. In this way the passivating lithium salts can be concentrated on the surface. In many instances only the pigment surface produces passivating influences on the substrate. Since molecules on the surface are a very small percentage on the order of one atom to then-thousand interior atoms the amount of passivating chemical can be much less. A patent application is also being prepared on this concept. This concept is called 'nanostructural inhibitors'. The second objective is to incorporate these inhibitors into a paint vehicle as primers. An arrangement has been made with 'EuroNavy USA' for this phase which has not yet begun. They will test and manufacture the paints. The final objective is to accommodate the products to Navy requirements for various paint specifications where possible. We have already tested some of the proposed passivators on 1000, 2000, 5000 and 6000 series alloys successfully.