Recently we spoke with Adam Goff about the need for environmentally-friendly coating alternatives to protect high-value assets in the aerospace, energy, and transportation industries. The problem? Galvanic corrosion is a menace to any aircraft, infrastructure, or vehicles made of aluminum and other metals. One of Luna Labs’ most recent protective coatings is Blockade™ GC, a non-chrome and non-hazardous corrosion control coating that minimizes galvanic corrosion attack around mechanical fasteners and other dissimilar metallic interfaces.
LL: You are an expert in galvanic corrosion. Could you explain what it is and why it is a significant issue for defense and other industries?
AG: Galvanic corrosion occurs when two dissimilar materials (usually metals) are in close proximity to one another (or in direct contact) and electrolyte (e.g. saltwater, condensation) is present. A galvanic battery sets up where electric current will flow between the metals, causing one to corrode (the anode) while the other does not (cathode). The rate of galvanic attack is largely dictated by how cathodic the other metal is in terms of potential and current carrying capacity. The greater the potential difference and higher cathodic current capacity, the greater the galvanic attack of the anode.
Galvanic corrosion literally affects just about every industry. A common example is around the multitude of mechanical fasteners and attachment points that can exist across numerous structures (e.g. aircraft, automotive, bridges, buildings, etc.). Every one of these dissimilar metallic regions can result in galvanic corrosion damage.
Galvanic corrosion between dissimilar metals (e.g. fasteners) represents a significant portion of total maintenance costs and upkeep for numerous industries. Historical approaches to controlling galvanic corrosion involve protecting the anode (e.g. usually painting), but minimal efforts have been made to limit the galvanic contribution at the cathode. There is a need for environmentally friendly protective coatings that are easy to apply and implement that offer next-generation protection.
LL: Tell us about Blockade GC. What’s the significance of a hybrid sol-gel coating? How is Blockade GC different than what is currently in use? What are its benefits?
AG: Historical coatings intended to limit galvanic attack have either contained hazardous chromate materials, and/or relied on sacrificial metallic pigments or platings to protect the structure. This has generally worked, but with increasing environmental and occupational health regulations, these chemistries are no longer acceptable. Additionally, a new approach to limiting galvanic attack, other than chromates and sacrificial approaches, gives more versatility and choices to end-users who need it.
Blockade GC is unique because it is based on a hybrid inorganic-organic sol-gel chemistry that is non- chrome and non-hazardous. This sol-gel coating offers an economical galvanic corrosion mitigation solution that is easily applied with long-lasting durability. The thin barrier coating (4-8 microns) ensures compatibility with various hardware types and can be installed on factory-sourced parts with minimal pre-treatment required.
With Blockade GC, we have the combination of excellent barrier properties associated with the inorganic coating backbone, combined with the toughness and flexibility of a polymer, resulting in a multifunctional performing coating that is extremely effective at limiting galvanic attack.
It functions by acting as an electrical barrier between components, hindering corrosion development, increasing durability, and improving overall performance. This eco-friendly, cost-effective coating can be factory applied or by a qualified applicator, allowing for direct installation of parts without extra steps.
LL: Why is it important that Blockade GC is a non-chromate coating?
AG: Blockade GC can provide chromate level galvanic protection in a fully non-chrome and non-hazardous coating stackup, making it a better option for people who work with coatings and for the environment.
LL: Blockade GC is the successful result of Department of Defense SBIR support. What was the critical need? How do you describe the value of the SBIR program in developing this innovative solution?
AG: Numerous aircraft and other assets across the DoD suffer from galvanic corrosion. It is a leading cause of reduced asset Operational Readiness and Non-Availability across the services. The development of Blockade GC is a next-generation galvanic corrosion mitigation technology that can help turn these problems around. This important technology has been enabled by the SBIR program through three different projects funded across the Navy and Air Force. Since the coating technology is an enterprise solution, it can be effective in numerous other non-DoD fields as well.
LL: How do you envision Blockade GC changing how we protect ships, airplanes, oil rigs, wind turbines, and so many other critical assets in the future?
AG: It can be used in numerous aircraft applications ranging from screws, bushings, rivets, and many other dissimilar metallic interfaces. When combined with other non-chrome pretreatments and primers, Blockade GC has been demonstrated to significantly exceed the galvanic corrosion protection performance of traditional legacy (hazardous) chrome-based coating systems. It can uniquely enable a fully non-chrome material aircraft stackup where other non-chrome materials have failed.
The energy industry is one of the most challenging based on the often-severe environments in which equipment and assets must perform. This can range from highly acidic media, corrosive salt water (e.g. seawater), hazardous and corrosive chemicals, high pressure, and wide temperature swings. Blockade GC can survive extremely harsh conditions and find application wherever galvanic corrosion protection is a concern.
Adam Goff is an established materials researcher specializing in hybrid coatings and composites. With expertise in electrochemistry, inhibitor chemistry, electromagnetics and nanomaterials, Adam leads efforts to develop novel advanced coatings to tackle the destructive effects of corrosion.
Prior to his work at Luna Labs, Adam was a materials engineer at Teledyne Energy Systems. He received a BS and MS in Materials Science and Engineering from Virginia Tech.
Contact our advanced materials team to discuss how Blockade™ GC or our other protective coating solutions can address your corrosion and repellency needs.
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