Examination of Nonchromate Conversion Coatings for Aluminum Armor From Three Final Candidates Using Accelerated Corrosion and Adhesion Test Methods

This study examines the effectiveness of three final candidate nonchromate conversion coatings on aluminum alloys 5083, 7039, and 6061 coated with standard solvent-based Chemical Agent Resistant Coating CARC system. The nonchromate conversion coatings examined were Cape Cod Organosilane, Brent Oxsilan AL-0500, and Henkel Alodine 5200. Evaluation methods included American Society for Testing and Materials ASTM standard B117 ASTM. Standard Method of Salt Spray Fog Testing. ASTM B117, West Conshohocken, PA, 1990 salt fog, General Motors GM 9540P GM. Accelerated Corrosion Test GM 9540P. GM 9540P, GM Engineering Standards, 1997 cyclic salt spray, ASTM D3359A ASTM. Standard Test Methods for Measuring Adhesion by Tape Test. ASTM D3359, West Conshohocken, PA, 1987 wet adhesion, ASTM D3359B dry adhesion, ASTM D4541 ASTM. Standard Test Method for Pull-Off Strength of Coated Specimens Subjected to Corrosive Environments. ASTM D4541, West Conshohocken PA, 1989 pull-off adhesion, and exposure at the U.S. Army Aberdeen Test Center ATC automotive test track. Specimens examined consisted of flat test panels as well as actual components used in M2M3 Bradley Fighting Vehicles Systems. Additional Panels and components were exposed for 4000 mi on actual fielded Bradleys at Camp Roberts, CA, and examined after exposure for degradation and adhesion. The ultimate goal of this study is to choose the best overall substitute for hexavalent chromium based Alodine 1200 which is currently in use and is known to be harmful to the environment and a health hazard.