Hexavalent Chromium (Cr(VI)) Elimination: It's More Than Just Primers

Much of the research, development, test and evaluation (RDT&E) activities to date targeting the elimination of hexavalent chromium (Cr(VI)) in DoD applications has focused on the development or qualification of a chrome-free primer.  This makes perfect sense since some estimates indicate that up to 70% of the Cr(VI) use by volume on DoD weapon systems is due to the use of the current chrome primers.  However, if the total elimination of Cr(VI) is the goal, much more attention needs to be paid to all of the other myriad applications of Cr(VI) in the DoD.

This paper will focus on the current Air Force initiative to develop technology roadmaps to eliminate Cr(VI) from all weapon system applications.  Included will be the Air Force’s experience with weapon system applications that utilize Cr(VI) including: application of hard chrome (line-of-sight (LOS), and non-LOS), conversion coatings and pretreatments, sealants, bonding primers and wash primers.  The paper will summarize the RDT&E activities to identify alternatives for each of these uses and present the current path forward in reducing or eliminating Cr(VI) in each application area.  Included will be a discussion of why one solution does not fit all, and why the alternatives for Cr(VI)-containing materials and processes must be application-specific.  Finally, this paper will address primers by detailing Air Force initiatives to evaluate in the field, a totally chrome-free paint system.