Abstract
In this paper, a novel method combining electrochemical impedance spectroscopy (EIS) and phase shift was used to systematically study the effect of corrosion inhibitor (sodium succinate, sodium dodecyl benzene sulfonate, and new corrosion inhibitor, namely, bis [2-amino-3-(dodecyl dimethyl quaternary ammonium) propyl]-propylamine dichloro) on crack initiation and propagation of aluminum alloy during the slow strain rate tensile process. Using a variety of characterization methods to verify the feasibility of using the new method for in-situ prediction, Kramers–Kronig transformations have been used to validate the experimental data obtained with the EIS measurements. The corrosion inhibition mechanism of these three kinds of inhibitors in the SSRT process was analyzed.
Highlights
Aluminum alloys are widely used in the aerospace field for aircraft fuselages, skins, and landing gear. e service environment of the aircraft is very complex
A new corrosion inhibitor was synthesized. e effect of three corrosion inhibitors on the crack initiation, and propagation of 7A04 aluminum alloy during the Slow Strain Rate Tests (SSRTs) process was studied by combination of electrochemical impedance spectroscopy (EIS) and phase shift
E feasibility of this novel method to predict crack initiation and obvious propagation time is proved by SEM, EDS, and metallographic experiments. e inhibition mechanism of three types of corrosion inhibitors is inferred. e results are as follows: (1) e results of EIS show that the tensile stage is divided into four periods: metal dissolution, crack initiation, dynamic equilibrium, and crack propagation. e phase shift method shows that the moment when the phase shift difference at 10 Hz, 100 Hz, and 1000 Hz peaks is the moment when the crack initiation appears and obvious propagation time of aluminum alloys
Summary
Aluminum alloys are widely used in the aerospace field for aircraft fuselages, skins, and landing gear. e service environment of the aircraft is very complex. Erefore, it is of great significance to improve the reliability and safety of the aircraft by studying the corrosion initiation and propagation of corrosion inhibitors for aerospace aluminum alloys under mechanical-corrosion coupling and understanding the mechanism of corrosion inhibition. Bosch [3] gave an equivalent circuit description of the crack impedance model and showed that the evolution of the impedance phase at certain frequencies may be related to the occurrence of SCC, establishing the possibility of inferring crack initiation using the phase-shift method. It does not give a good prediction of the crack obvious propagation of the alloy.
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