Effect of Laminar Flow on the Corrosion Activity of AA6061-T6 in Seawater

Abstract

The electrochemical behaviour and surface changes on AA6061-T6 alloy exposed to Caribbean seawater from the Cozumel Channel for 30 days under laminar flow (0.1 m s−1) were studied, contrasting then with stationary (no flow) conditions. Monitoring of open-circuit potential and current fluctuations, both considered as electrochemical noise (EN), were employed as two nondestructive methods. The calculated corrosion current, based on Rn, was one order higher in laminar flow. The fluctuations of current were transformed in the frequency domain. Their power spectral density (PSD) plots were obtained in order to gain information concerning the dynamic of the spontaneous release of energy during the corrosion process. The value of the exponent β in PSD graphs suggested that the localised corrosion on AA6061-T6 surface occurs as a persistent stationary process, in which dynamic is controlled by oxygen diffusion and its renewal at the metal interface. The changes in the morphology and elemental composition of the formed layers revealed that the localized attacks occurred in the vicinity of intermetallic particles rich in Fe and Cu, which act as cathodes.

Assessment of dissimilar joining between metal and polymer hybrid structure with different joining processes

“…43,44 Because less heat is produced, there is no cracking and little distortion of the base material. 45 Table 1 depicts various welding processes and their requirements.…”

The Application of Electrochemical Noise for the Study of Metal Corrosion and Organic Anticorrosion Coatings: A Review

“…[42] In addition, L. Veleva, G. Acosta and J. L. López applied the PSD spectrum of potential noise to analyze the corrosion of 6061-T6 and 2219-T42 aluminum alloys in Caribbean seawater. [43][44][45] The decrease of the β exponent in PSD graphs indicated a release of spontaneous energy with the progress of pit formation in seawater. The fluctuations were associated with the breakdown and formation of new corrosion layers.…”