Experimental Evaluation and Modeling of Galvanic Interactions between Aluminum Alloy 7075-T6 and Noble Materials

Abstract

Galvanic interactions between aluminum alloys and noble materials in corrosive environments can cause structural problems in the use of military and commercial assets. The aim of the current work is to determine the conditions that lead to significant localized corrosion by galvanic coupling and to understand its controlling mechanism. The cathodic kinetics of noble materials (silver, nickel and carbon-fiber reinforced bismaleimide (BMI)) and the dissolution kinetics of aluminum alloy AA7075-T6 were quantitatively investigated and used as boundary conditions for a numerical study. Finite element analyses were used to study the galvanic interactions of AA7075-T6 and noble materials in a geometry modeled on a two fastened plates as a function of solution pH and chloride concentration [Cl-]. The results in the paper indicated that both initiation and propagation of localized corrosion were influenced by the galvanic interactions, and these were evaluated as a function of geometry, noble material, and solution composition.