PPG Industries, Inc. (PPG) will demonstrate and validate the novel system consisting of hexavalent chromium-free (HCF) primer + modified topcoats for use over aluminum alloys in relevant Department of Defense (DoD) environments. The system will be shown to be both environmentally acceptable, (no heavy metals such as Hexavalent chromium [Cr6+] or Nickel [Ni]), and an effective alternative to existing hexavalent chromium based primers and current military standard approved topcoats for DoD assets. Validation and demonstration will be completed in cooperation with Air Force Research Laboratory (AFRL) and Naval Research Laboratory (NRL) using both conventional field testing and developmental accelerated test methodologies. At the conclusion of the program, sufficient data will be generated to facilitate adoption of both the coating system and the test methodologies.

Technology Description

PPG has developed a HCF coating system where both the primer and the topcoat contain corrosion inhibitor(s), and where the inhibitor(s) in the primer layer are of a distinctly different type than the inhibitor(s) in the topcoat layer. This overcomes limitations of conventional coatings with leachable inhibitors only in the primer layer, minimizes negative impacts from incompatibilities between the inhibitor and the coating matrix, and produces a synergistic effect between the two types of corrosion inhibitors. The net result is a coating system with corrosion protection comparable to that of chromium-containing coatings, and significantly lower toxicity.

The project will demonstrate the efficacy of the coatings for aluminum substrates, both for outer moldline and structural components. A successful project will generate sufficient data, both through conventional field testing and accelerated testing, to validate performance and allow for demonstration activities at larger scale that facilitate widespread DoD adoption of the technology.


The HCF primer/topcoat system has the potential to be transitioned to any DoD facility that paints components. Data generated in the demonstration will enable quantification of the benefits of the coating system, both from an asset protection standpoint as well as through reduction of occupational exposure risk. As the coatings are based on current commercial and military-approved primers and topcoats, they do not entail additional manufacturing or maintenance complexity. In addition to validation of the coatings, the project serves as a test bed to demonstrate and quantify the enhanced speed and accuracy of novel test methodologies. A more rapid, accurate means of predicting novel coating performance will reduce the amount of time required to introduce new corrosion protection technologies to DoD organizations, and reduce inherent risks of costly failures.