This projects seeks to demonstrate an emerging primer technology on Department of Defense (DoD) aircraft and validate that the laboratory performance in accelerated test methods correlates to enhanced airframe corrosion prevention. The goal is to demonstrate aluminum-rich primers that have a minimum of 25% greater protection against galvanic corrosion.
Based on the need for more durable, corrosion resistant, and safer primers and topcoats, the Office of Naval Research (ONR) began investing in research and development efforts at the Naval Air Warfare Center, Aircraft Division, whose research has focused on new primers based on a novel aluminum-alloy inhibitor pigment. Researchers found that epoxy primers with the aluminum anode alloy pigment included as the main corrosion inhibitor exhibited significantly better protection against galvanically driven corrosion than both leading chromate and non-chromate based commercial aerospace primers.
An ONR program is currently funding three companies to scale up production of primers based on this aluminum-rich technology, as well as funding the Navy and Marine Corps to evaluate the deliverable commercial products for those performer’s program contracts. This program seeks to act as a follow-on to this ONR program by demonstrating similar products on aerospace assets from multiple DoD services, with a slightly improved environmental footprint. To date, the best products tested have included particles which were passivated using a trivalent chromium conversion coating process. Here, the project team plans that a simple raw material change, which utilizes a non-chromium containing passivation process, will be adopted by the manufacturers. Each services’ respective laboratories will prove the change does not affect corrosion protection in accelerated tests, followed by a validation of the maturity of the primers by entering a field demonstration on various aircraft from multiple DoD services in their respective operating environments.
Corrosion is a major degrader for every DoD service, and nearly every aviation platform. Data collected regarding costs to the DoD regularly show each service spends billions of dollars yearly mitigating corrosion on aircraft, and the best materials currently available to protect these assets are toxic. Resultantly, aircraft mission availability is low, following nearly two decades of high tempo operations and deferred maintenance. Should the demonstration project here prove the technology is capable of meeting the project team's goals, the benefits will address the key metrics of aircraft reliability and maintainability, overall program costs, and compliance with environmental restrictions (especially in foreign partner countries where Registration, Evaluation, Authorization & Restriction of Chemicals sunset dates for hexavalent chromium are fast approaching). Past efforts to replace chromate containing coatings with alternatives acknowledged that performance deficits are potential, if not explicitly accepted, as a result of implementing non-chromate materials. Here, the project team seeks to reverse that course, and deliver protective coatings that protect the aircraft even better than chromate, while at the same time meeting all near term environmental regulations.
NAVAIR Public Release 2021-94. Distribution Statement A - Approved for public release; distribution is unlimited.