Performance of Chrome-Free Paint Systems In Field and Lab Environments -- Summary of 4 Years of Flight and Ground Exposures

Performance of Chrome-Free Paint Systems In Field and Lab Environments – Summary of 4 Years of Flight and Ground Exposures

Abstract

As part of several evaluation programs, over 60 paint systems have been evaluated in outdoor ground, flight, and laboratory exposures.  The majority of these have involved paint systems totally free from chromates.  Samples were in the form of painted and scribed 2024 T3 aluminum panels and similar corrosion sensors.  These together with several other special configurations have been exposed to the severe, seacoast site at Daytona Beach, Fl.  In addition, painted and scribed corrosion sensors have been flying on upper fuselage for up to 4 years on C130, C5, and HC144 aircraft.  Additional sensors were flown on various locations on H60 helicopters including what has been demonstrated to be the exceptionally severe conditions on the underbelly of USAF Rescue helicopters.

These results have shown that very few new, non chrome paint systems will survive or even perform favorably compared to a conventional coating with chromate pretreatment and primer plus an 85285 topcoat.  However, one relatively new coating system containing a magnesium-rich primer (and chrome-free pretreatment) has shown excellent performance under all test conditions.  Results obtained to date indicate that in some tests, this material may exceed the performance of a system with chromate and in other tests may not be “quite as good”.  These results may require future considerations of better definitions of what constitutes “good enough”.  In addition, all of these results suggest that the users of any of these new paint systems must begin to consider their use in relation to the probable environmental severity range for different platforms.