Alternative Chromate-Free Wash Primers
Final rept. Feb 2002-Jul 2006
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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The purpose of the DOD-P-15328D wash primer is to enhance corrosion resistance, through the passivity of the metal surface. In the U.S. Armys Chemical Agent Resistant Coating CARC System, the metal surface is coated with a wash primer, over-coated with an epoxy primer, and followed by a camouflage urethane topcoat. Several coating procedures specify the use of wash primer DOD-P-15328D as a surface treatment prior to the application of an epoxy primerpolyurethane topcoat CARC system. The current wash primer is low-solids, solvent-based polyvinyl butyral that contains phosphoric acid and zinc chromate to promote adhesion and minimize corrosion. This coating contains large amounts of volatile organic compounds VOCs and hazardous air pollutants HAPs that impact coating operations due to air pollution regulations that may require the use of control devices to reduce the total VOCHAP emissions to the atmosphere. The U.S. Army Research Laboratory has evaluated new, water-reducible wash primers that do not contain hexavalent chromium and significantly minimize potential VOC and HAP emissions during coating operations. Coatings have been extensively tested for accelerated corrosion and adhesion and have completed 3 years of outdoor exposure testing. Tests are now required on military equipment to validate the lab and controlled testing previously completed. The ultimate objective of the process is to demonstrate that the low-VOC wash primers can provide a drop-in solution to the environmental issues associated with the solvent-based primer currently in use, providing equal or better performance, involving no significant changes to the application and stripping procedures currently used. The field demonstration of this coating was conducted at Letterkenny Army Depot facility, prepared on an Engagement Control Station Patriot truck unit.
- Coatings, Colorants and Finishes
- Properties of Metals and Alloys