Plasma Electrolytic Diffusion Treatments for Reduced Electrochemical Current Density in Aircraft Structural Fasteners

Modern aircraft make extensive use of fasteners made of steel, titanium, nickel and other alloys mated with aluminum and composite airframe materials. This coupling of dissimilar materials yields galvanic corrosion issues, which degrades mechanical integrity, is costly to inspect, and poses a safety and reliability risk. Traditional design approaches of corrosion rate predictions based on open circuit potential (OCP) do not account for realistic adaptations such as the current density in the coupling. The cost of these poorly predicted galvanic corrosion issues is great not only in the labor required to inspect and maintain the structures, but also in the cost of fleet readiness. In order to improve corrosion resistance to critical aerospace fasteners, IBC Materials and Technologies and The Ohio State University will tailor the surface chemistry of fastener materials using the innovative Plasma Electrolytic Diffusion (PED) process. Together with OSU, IBC will perform surface alloying of corrosion resistant steel (CRES) materials in order to reduce galvanic potential and impede cathodic current in working designs. The versatile PED process promises a revolutionary new approach to reduce fastener corrosion and yield significant savings to military and commercial aircraft.