Advanced Surface Engineering Technologies for a Sustainable Defense (ASETSDefense) is an initiative funded by SERDP and ESTCP to facilitate the implementation of environmentally benign surface engineering technologies. As part of this initiative, SERDP and ESTCP sponsored ASETSDefense 2014: Sustainable Surface Engineering for Aerospace and Defense, a technical workshop that provided attendees from DoD, industry, and academia the opportunity to exchange information related to the testing and implementation of environmentally friendly coatings and surface treatments.
Dr. Jeffrey Marqusee of Noblis gave the Keynote Presentation, “Advancing Sustainable Surface Engineering: Challenges & Future Opportunities.” He noted that the biggest return on investment is achieved when toxic materials can be eliminated across an entire shop floor by using technologies that improve performance or lower costs. To accomplish this, advanced computational and testing methodologies are needed to optimize processes, accelerate transitions, and predict lifecycle results. Several posters and briefings presented at the Workshop detailed examples of computational development and modeling and improved testing:
- Boeing is beginning to use multi-scale modeling for material design, computational methods for accelerating science-based solutions, and modeling tools for paint system development.
- The Office of Naval Research’s Sea-Based Aviation Program is developing computational methods to eliminate corrosion and stress corrosion cracking in the design phase, starting with corrosion simulation and prediction.
- Corrdesa, LLC is developing computational methods to reduce risk when adopting new technologies.
- Air Force Research Laboratory is developing improved accelerated corrosion test methods.
The elimination of cadmium (Cd) and hexavalent chromium (Cr6+) is a significant challenge and each of the Services has ongoing efforts to replace these materials. NAVAIR’s approach in their Engineering Circular is to test and qualify alternatives in successively higher risk locations, as knowledge and experience expand. Fleet Readiness Center - South East has determined that complying with OSHA Cr6+ regulations costs $1 million per year. This estimate is part of a new SERDP and ESTCP Advanced Coatings Initiative seeking to achieve complete replacement of Cd and chromates across entire depots. Outside of DoD, the Highly Innovative Technology Enablers for Aerospace (HITEA) program is evaluating commercial options for aerospace.
Flight tests and approvals include demonstrations of non-chrome primers on Coast Guard helicopters, zinc-nickel electroplating replacing Cd on landing gear and fasteners, and implementation of Tagnite to protect magnesium gearboxes on C-130 engines.
In addition, some interesting new technologies are being developed at laboratories around the world. A U.S. technology for trivalent hard chrome plating, which had eluded researchers for decades, is finally looking viable. The nanophase cobalt plating technology developed by a Canadian company is finding applications, not just as a hard chrome replacement but also in electroformed bushings. A drop-in additive to standard plating baths that produces nano-composite coatings without alteration to the existing plating process has been developed in New Zealand, and looks capable of significantly increasing hardness and wear resistance. A new sol gel surface treatment from France has now finally succeeded in incorporating corrosion inhibitors into a paint adhesion promoter.
Yet even if Cr6+ is eliminated entirely from DoD applications, it remains on many legacy systems. To eliminate the risk of exposure during depainting operations, the U.S. Air Force is implementing a robotic laser for depainting outer mold lines, while Battelle has developed a chemical to reduce hexavalent chromium to less toxic trivalent chromium in the dust from paint sanding operations.
Presentations and posters from the workshop are available on the ASETSDefense website.