Durable Sol-Gel Surface Treatment to Control Cathodic Current Density

There are numerous regions across modern aircraft that necessitate advanced corrosion solutions in order to protect and maintain their readiness. One such application is the numerous cathodic fasteners that are galvanically coupled to anodic structural materials, like high-strength aluminum alloys. There is a need to bolster corrosion protection at these locations via a user-friendly surface treatment technology that is extremely durable and easy for maintainer application. Luna has developed a durable sol-gel surface treatment solution for this problem that is designed to reduce galvanic corrosion by i) providing excellent physical barrier protection against moisture and corrosive ions, and ii) imparting a durable and dense electrically insulating layer between mated components. This sol-gel treatment is inherently chrome-free and consists of a non-hazardous chemistry that results in a highly cross-linked inorganic/polymer hybrid film with excellent impact resistance, flexibility, and toughness. In Phase I, Luna demonstrated significantly reduced corrosion during accelerated galvanic fastener testing with sol-gel treatments applied to two of the most aggressive cathodic aircraft materials: 316 stainless and 4140 high strength steel. The team will build on this progress to optimize and extensively characterize the surface treatment and fastener application process during the Phase II.