Prepared for University of Rhode Island Transportation Center Replacement of Chromates in Paints and Corrosion Protection Systems

DISCLAIMER This report, prepared in cooperation with the University of Rhode Island Transportation Center, does not constitute a standard, specification, or regulation. The contents of this report reflect the views of the author(s) who is (are) responsible for the facts and the accuracy of the data presented herein. This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. This technical report presents the first stage results of a multi-year project to develop chromate-free paints and corrosion protection systems. Chromate coatings and chromate-containing paints are very effective in providing corrosion resistance and are widely used in the manufacturing, transportation and defense industries; however, there is a need to find an environmentally-and occupationally-friendly replacement to chromate (chromium VI is considered a carcinogen with an extremely low personal exposure limit). The tasks of this first stage consisted of the scale-up and corrosion testing of an alternate-to-chromate coating, initiation of biocorrosion tests, and development and corrosion testing of a wash primer. The alternate-to-chromate coating involves substituting titanium for chromium (titanium is much safer than chromium and it is used for hip replacement in humans). The new formulation protects in the same manner as chromate and has been able to match the test data for chromated surfaces. Microbially-influenced corrosion (biocorrosion) studies were initiated by establishing marine bacteria cultures and conducting preliminary electrochemical impedance spectroscopy measurements. A wash primer containing polyaniline (an electroactive polymer) instead of chromate was also developed and corrosion tested. The report ends with a summary of future tasks to further develop chromate-free paints and anti-corrosion systems.