EIS study on pitting corrosion of 7150 aluminum alloy in sodium chloride and hydrochloric acid solution

Abstract

The pitting corrosion behavior of 7150 aluminum alloy was studied by electrochemical impedance spectroscopy (EIS) in the sodium chloride and hydrochloric acid solution. Based on EIS features and corrosion morphologies as well as corrosion potential, the process of pitting corrosion could be clearly divided into four stages: at the first stage, the Nyquist diagram was composed of two overlapping capacitive loops at the high-medial frequency and one inductive loop at the low frequency. At the second stage (metastable pits developing stage), there existed one small capacitive loop at the high frequency and one big capacitive loop at the medial frequency. At the third stage (stable pits developing stage), two time constants were more clearly distinguished, corresponding to two obvious capacitive loops. At the fourth stage, there appeared one capacitive loop, attributing to uniform corrosion. An equivalent circuit was designed to fit EIS, and the experimental results and the fitted results had good correspondence.

Electrochemical behavior of hydrophobic silane–zeolite coatings for corrosion protection of aluminum substrate

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Influence of multi-step heat treatments in creep age forming of 7075 aluminum alloy: Optimization for springback, strength and exfoliation corrosion

“…In order to give quantitative support to experimental results and better explanation about the susceptibility to corrosion, impedance parameters were obtained by the Zview software using an equivalent circuit model [20,21], drawn in the inset of Fig. 6b.…”

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