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Collaborative Research: Hex Chrome Free Bond Primers

Bond primers containing hexavalent chromium compounds are currently being used in aerospace manufacturing with several different combinations of surface preparations, substrates, and adhesives.  The bond primers are used to improve the adhesion of structural bonds and historically have included hexavalent chromium as a corrosion inhibitor. Hexavalent chromium contained in these bond primers is prohibited in applied materials in concentrations over 0.1% under the 2011 Defense Federal Acquisition Regulation Supplement (DFARS), “Minimizing the Use of Materials Containing Hexavalent Chromium”.   In 2014, a Hexavalent Chromium Free Bond Primer Evaluation Team was established to identify, test, and evaluate various safer commercially available bond primer materials. The team includes representatives from the following organizations:

  • Air Force
  • Boeing
  • Bombardier
  • GE Aviation
  • Harris
  • Lockheed Martin
  • NASA
  • Northrop Grumman
  • Piper
  • Pratt & Whitney
  • Raytheon
  • Sikorsky
  • Textron Aviation
  • University of Massachusetts Lowell - TURI
  • UTC Aerospace 

The goal of this effort is to produce a Joint Test Protocol with the intention of ultimately providing the data necessary to justify the use of DFARS-compliant hexavalent chromium free bond primers for aerospace applications.  MMM-A-132 is the primary specification used as a guide for testing and acceptance criteria.  This effort is intended to eventually become designated as a NASA Technology Evaluation for Environmental Risk Mitigation (TEERM) project.