Atmospheric corrosion behavior of 7A09 aluminum alloy exposed to an industrial environment

Abstract

The corrosion behavior of 7A09 alloys exposed to an industrial atmosphere for 36 months was studied by weight loss method, morphology observation, electrochemical method, and loss in mechanical properties. Under the condition of exposure to an industrial atmosphere, the 7A09 alloy suffers obvious pitting corrosion and intergranular corrosion (IGC), and a charge transfer process controls the corrosion reaction. The corrosion rate presents a decreasing tendency with exposure time, which is mainly due to the enhancement of the protective ability of the corrosion product layer. The occurrence of IGC of this alloy is mainly caused by the preferential dissolution of the grain boundary precipitates Mg(ZnAlCu) 2 and the precipitate-free zone along grain boundaries, and which leads to the reduction of the mechanical properties. In addition, the morphology and composition of the corrosion product layer were identified, and the corrosion mechanism was also discussed.

Effect of Alkyl Chain Length on the Corrosion Inhibition Performance of Imidazolium-Based Ionic Liquids for Carbon Steel in 1 M HCl Solution: Experimental Evaluation and Theoretical Analysis

“…CPE represents the constant phase angle used to replace the ideal capacitance ( C ), thus obtaining a more accurate fitting curve. CPE1 and CPE2 represent the film capacitance and the double-layer capacitance, respectively, and the corresponding values can be calculated by the following equations: Z CPE = Y 0 − 1 false( j ω false) − n C dl = Y 0 false( 2 π f max false) n − 1 where Y 0 is the CPE constant, ω represents the angular frequency, j denotes the imaginary number, n corresponds to the CPE exponent, and f max indicates the frequency at which the imaginary part of the impedance reaches its maximum. The C dl can also be calculated by the following equation: C dl = true ε 0 ε S d where d represents the thickness of the double layer, ε 0 and ε denote the permittivity of air and the local dielectric constant, respectively, and S is the surface area of the electrode.…”