Performance of Chromate-Free Pretreatment Options for CARC Systems

摘要

Chemical agent resistant coatings (CARC) are required on all tactical and support equipment. These camouflage coatings meet the survivability criteria by resisting penetration of the paint film by chemical agents and make decontamination easier. Research efforts are primarily aimed at prevention and early detection of corrosion to maintain readiness and minimize life cycle cost. Another aspect associated with environmentally friendly coatings that are hazardous air pollutant (HAP)-free and low volatile organic compounds (VOC) is the high cost of solvents that meet the EPA criteria. Recently, the U.S. Army Research Laboratory developed a water-reducible two- component polyurethane CARC topcoat, MIL-DTL-64159, that will replace the U.S. Army's standard two-component, solvent-based CARC, MIL-C-46168. The water dispersible coating reduces VOCs by 50% and eliminates HAPs. The alternative, MIL-DTL-53039, is a solvent-borne aliphatic polyurethane that is HAP-free and low VOC. The development of these new and improved coatings have multifunctional performance requirements and need to withstand the most severe environments. Therefore, the need for effective corrosion control and detection lies at the center of our coatings research. The resistance of the coatings to corrosion was assessed using continuous exposure to salt fog per ASTM B117 and cyclic exposure per GM 9540P. Critical coating assessments including impact resistance and wet and dry adhesion were used as a basis to characterize and predict the performance of the coating. This report documents metal substrate selection, application techniques, and laboratory testing procedure.