Inhibition of O₂ reduction on intermetallic particles at the surface of AA2024 by adsorbed phosphonates

Aluminum alloys are important technological materials with applications in many areas because of their light weight and high strength. However, the presence of intermetallic particles (IPs) on the surface of these alloys makes them susceptible to corrosion. We have recently shown that O₂ reduction at these IPs causes the local production of OH^-, which etches the natural oxide layer around the IP and starts the corrosion process. In this paper we describe the adsorption of various phosphonates at the surface of AA2024 and their inhibitory effect toward the reduction of O₂. Both rotating disk and wall-jet voltammetry are used to demonstrate a reduction in O₂ cathodic current density from adsorbed phosphonates of two orders of magnitude.