Synergistic Erosion and Corrosion Behavior of AA5052 Aluminum Alloy in 3.5 wt% NaCl Solution Under Various Impingement Angles

Abstract

Erosion–corrosion behavior of AA5052 aluminum alloy was studied in 3.5 wt% NaCl solution containing silica sand as erodent particle. The tests were carried out according to ASTM G119-09 standard using a slurry jet apparatus at a jet velocity of 3 m/s, sand concentration of 90 g/l, and various impingement angles of 25°–90°. The pure erosion rates were also obtained using cathodic protection of the samples during erosion–corrosion tests. Results showed that maximum pure erosion and erosion–corrosion rates occurred at impingement angle of 30°. On the other hand, a negative synergism rate was obtained under all conditions tested. Energy dispersive spectrometry analysis suggested that the negative synergism could be attributed to the existence of a protective oxide layer formed on the eroded surface of the samples during erosion–corrosion tests. Results also showed that corrosion rates during flow corrosion (i.e., no sand) and erosion–corrosion were much higher than the pure corrosion rate in a stagnant condition. Furthermore, there almost was no change in the corrosion rates at various impingement angles of 25°–90°. Scanning electron micrographs showed erosion features like raised lips and wear tracks at the impingement angle of 30°, and plastic deformation due to particle impact at the impingement angle of 90°.