Long-Term Accelerated Corrosion and Adhesion Assessment of CARC Prepared Aluminum Alloy 5059-H131 Using Three Different Surface Preparation Methods; Final rept. May 2007-May 2008

摘要

Aluminum alloy 5059-H131 panels rolled to 0.25-in thickness were prepared using chemical agent resistant coating (CARC) for evaluation under three different pretreatment conditions. The pretreatment conditions were abrasive blasted; a nonchromate pretreatment, Alodine 5200; or a commercial trivalent chromate pretreatment, Metalast TCP-HF. The primer used was MIL-DTL- 0053022C and the topcoat was MIL-DTL-53039. Corrosion resistance was evaluated under GM 9540P and ASTM B 117 neutral salt fog (NSF) methods for durations well beyond what is typical for most substrates and coating systems. The extended durations were one full calendar year for NSF and 400 cycles for GM 9540P. Adhesion was assessed under dry conditions using ASTM D 4541 pull-off and under wet conditions using ASTM D 3359A. Prior to coating, the conversion coated surfaces were compared for uniformity and color vs. identically prepared AA5083 samples to determine whether or not the alloy differences will warrant modifications to current pretreatment processes.