Measuring streaking rates of an Al–Zn alloy using a difference imaging technique

An in situ difference imaging technique was used to measure the linear- and area-velocity of streaking corrosion on aluminum alloy AA7075 in chloride solutions. These velocities are difficult to assess by direct observations. Both the linear and area velocities of corrosion streaks strongly depended on the concentration of the chloride solutions. The area velocity decreased at higher chloride concentrations, whereas linear velocity increased. The differences in dependencies on chloride were considered to result from changes in the concentration of dissolved oxygen in the solutions.