Corrosion protection of AA2024-T3 by LDH conversion films. Analysis of SVET results

Abstract

In this work the protective effect of layered double hydroxide (LDH) films directly grown on the surface of 2024-T3 aluminium alloy is investigated using electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET).The SVET results focused on the localised nature of the corrosion process and are in agreement with the global response measured by EIS. Furthermore, the evolution of active corrosion protection rendered by LDH films is surveyed at microscale for the first time for long immersion periods in NaCl solution and in the presence of induced defects. The quantitative information provided by SVET is discussed and a parameter to describe the degree of corrosion localisation is introduced based on LDH systems.

A Novel Approach to Fabricate Protective Layered Double Hydroxide Films on the Surface of Anodized Mg‐Al Alloy

“…In addition, the content of impurity phase is less. Tedim et al fabricated ZnAl‐LDHs on aluminum alloys by introducing into Zn 2+ containing aqueous solution. The results showed that the surface is covered by a thin film separated by micrometer‐sized islands where LDHs are concentrated.…”

Active corrosion protection by a smart coating based on a MgAl-layered double hydroxide on a cerium-modified plasma electrolytic oxidation coating on Mg alloy AZ31

“…The photographs after 21 days of immersion show that there was corrosion only at the edges of PEO-Ce-LDH, whereas there was no obvious corrosion for PEO-Ce-LDH-P.3.4 Self-healing abilityEIS spectrum gives the averaged global electrochemical response of the specimens. In contrast, a localized technique such as SVET can provide the localized electrochemical behavior, including the magnitude and distribution of the anodic and cathodic activity on the corroding surface[55]. In order to evaluate the self-healing ability for different specimens, artificial defects were introduced into the coated specimens by a sharp knife.Fig.…”

Hexacyanoferrate‐Intercalated Layered Double Hydroxides as Nanoadditives for the Detection of Early‐Stage Corrosion of Steel: The Revival of Prussian blue

“…Most works published so far following this corrosion detection strategy use local pH changes near the surface of the substrate. This is particularly relevant in metal alloys where corrosion is of localized nature and pH near anodic and cathodic reaction sites can differ in several units , . Hence, the availability of a pH indicator in the vicinity of a corrosion site may allow a visual indication of the corrosion processes, before corrosion products are formed.…”