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Number of Pages 426i REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503 Final, 6/29/1996 -3 The primary objective of this research project was to provide an alternative corrosion protection through means of processes more environmentally benign than conventional methodologies. Hexavalent chromium (Cr+6) has historically been acknowledged to exhibit the technological forefront in corrosion protection of aluminum alloys. The Systems Approach Interface Engineering (SAIE) concept, adopted in this project, emphasizes the fact that the corrosion protection of a metal depends on the overall corrosion protective behavior of an entire systems, including the bulk characteristics of the coatings(s) and interfacial factors. The primary methodologies used were plasma processing. The technology showed superior corrosion resistant results to traditional aircraft coating systems. This technology is applicable to aircraft piece parts. • Milestones/Accomplishments -"Barrier-Adhesion" principle for damaged surface-and pitting-corrosion protections was established. -Equally good corrosion protection was obtained with E-coat and water-born spray primers without corrosion inhibitor, which out performed control with CC coating and a solvent borne chromated primer. -A hybrid process of IVD and cathodic plasma polymerization showed practical feasibility.
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MARCH 2001
REPORT TYPE AND DATES COVERED• Approach
Executive SummaryCorrosion on a coated aluminum alloy can be viewed as occurring based on the following two important modes of corrosion. 1). Corrosion that occurs at and in the vicinity of the damaged, or scribed, coating, which could be termed "damaged surface corrosion". 2). Corrosion that occurs under the undamaged coating, which often appears as many small pits. This corrosion can be referenced under the general category of "pitting corrosion".Examining over several thousands of corrosion test specimens, which were subjected to SO 2 salt spray and Prohesion salt spray tests through the course of this project, it became quite clear that the corrosion damage, which can be expressed by the width of corrosion along the scribed line or by the percent of corroded area...