Non-Chromate Conversion Coatings for Magnesium Alloys used in Automotive Industry

This SBIR Phase I project will evaluate the feasibility of using titanium- or vanadium-based compounds as chemical conversion coatings for magnesium alloys. Magnesium alloys suffer from high corrosion rates and must be coated with either an anodized or chemical conversion coating to minimize corrosion. This idea is based on knowledge gained by the Technology Applications Group, Inc. during the development of anodized coatings for magnesium alloys. It is anticipated that these coatings will allow the use of low-weight magnesium alloy in environmentally aggressive situations in automobile and aircraft applications. The objectives of Phase I are to: (1) prepare a series of titanium- and vanadium-based formulations, (2) apply the formulations to commonly used magnesium alloys, and (3) measure the salt spray corrosion resistance of unpainted magnesium alloys as well as salt spray scribe migration and paint adhesion of painted specimens. Phase I feasibility will be established if the company succeeds in formulating a coating that performs as well as or better than the widely used automotive chromate conversion coating, NH35. The most commonly used magnesium coatings are chromate conversion coatings. The toxicity and environmental aspects of chromates are well documented. The primary impact of this project would be the elimination of chromates from the metal finishing industries, which will allow automotive manufacturers to meet environmental mandates while allowing the continued growth of magnesium. Expanded use of magnesium would result in additional fuel savings and/or lower emissions.