Comparison of atmospheric corrosion behavior of Al‐Mn and Al‐Zn‐Mg‐Cu alloys in a tropical coastal environment

Abstract

Atmospheric corrosion behavior of 3A21 Al‐Mn alloy and 7A09 Al‐Zn‐Mg‐Cu alloy were investigated and compared. Electrochemical results, together with corrosion morphology characterization, suggest that in tropical coastal atmosphere, 3A21 and 7A09 alloys suffer pitting corrosion and intergranular corrosion (IGC), respectively, and 3A21 alloy shows better corrosion resistance and stronger repassivating capability than 7A09 alloy. The pit transition potential Eptp can be treated as criteria for susceptibility to possible forms of constricted localized corrosion for aluminum alloys. The IGC of 7A09 alloy is mainly caused by the preferential dissolution of the grain boundary precipitates Mg(ZnAlCu)2, and which results in fast deterioration in the mechanical properties of the field‐exposed samples. Besides, morphology and chemical compositions of native oxide layer and corrosion produces layer were characterized by SEM, EDX, and FT‐IR analysis, and the corrosion mechanism was also discussed.

The effect of temperature on corrosion behavior of AA5083 in brackish water and seawater

“…From measurement in brackish water, it can be observed that there is no significant difference between the curves and values. Slightly different shape of the curve at 25°C and the lower value of E rev can be associated with inhomogeneity of the alloy surface . From stated it could be concluded that temperature elevation does not have a major influence on the pitting corrosion values in brackish water and that pitting is probably associated with precipitates distribution on the surface.…”

“…It must be pointed that impedance of CPE, i.e. Q ox , is given with the following equation: where Z is impedance of Q ox , j is imaginary component, ω is the angular frequency, Y is the frequency independent admittance, and n is the power of Q ox . Since n value is >0.5 and close to one in all cases, it can be concluded that the oxide layer contains some pores…”

Corrosion inhibition of mild steel by the hydrolysate of an imidazoline-based inhibitor in CO2-saturated solution

“…j 2 = −1 represents the imaginary number and ω corresponds to the angular frequency in rad s −1 ( ω = 2π f ). The double-layer capacitance ( C dl ) and inhibition efficiency ( η %) are obtained from the following equations: 39 C dl = Y (2π f max ) n −1 where f max corresponds to the frequency at which the imaginary component of impedance is maximal. R 0 ct and R ct are the charge transfer resistances in the absence and presence of inhibitor, separately.…”

The Effect of Ecap Processing to Hardness, Surface Morphologi, and Corrosion Resistance of 6061 Aluminium Alloys

“…Aluminum alloys are well known for their high corrosion resistance because of their oxide film in the atmospheric environment [12]. Uniform, localized and pitting corrosions are the most common corrosion founded in aluminum alloys with a halide ion environment.…”