# Sebacate-Intercalated CaAl-LDH Pigments for Corrosion Protection of Aluminum Alloy

## TL;DR

This paper introduces a new corrosion inhibitor made from sebacate-intercalated LDH microparticles that significantly improves the corrosion resistance of aluminum alloys.

## Contribution

The novelty lies in synthesizing sebacate-intercalated CaAl-LDH microparticles for on-demand corrosion inhibition of aluminum.

## Key findings

- Sebacate-intercalated LDH microparticles showed high thermal stability and contained 21.2–27.6 wt% sebacate.
- The corrosion resistance of aluminum AA5005 was enhanced by ~40% reduction in corroded area and reduced filiform corrosion.
- Electrochemical tests showed increased pitting potential (E_pit) when using SB and LDH–SB, indicating better corrosion protection.

## Abstract

Layered double hydroxides (LDHs) have garnered significant
attention
in recent years due to their unique structure, which enables the intercalation
and controlled release of corrosion inhibitors in response to specific
stimuli relevant to corrosion processes. In this study, LDH microparticles
intercalated with sebacate (SB) were synthesized to function as a
corrosion inhibitor through on-demand release. The microparticles
were characterized using scanning electron microscopy, Fourier-transform
infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis
(TGA). TGA demonstrated that LDH has high thermal stability and that
the actual SB content in LDH/SB was estimated to be between 21.2 and
27.6 wt %. The effectiveness of calcium and aluminum-based LDHs intercalated
with SB as a corrosion inhibitor was evaluated on aluminum AA5005
substrates, both in bare form and coated with an acrylic layer. Accelerated
weathering tests revealing a reduction of approximately 40% of the
corroded area and a marked reduction in filiform corrosion during
constantly high relative humidity. A dilute electrolyte cyclic fog/dry
test also demonstrated a significant reduction in corrosion in dry/wet
cyclic aging. The SB species demonstrated potential as a corrosion-inhibiting
component under the studied conditions by enhancing the corrosion
resistance of the aluminum alloy. This performance was confirmed through
electrochemical characterization, including potentiodynamic polarization
measurements performed using an Ag/AgCl (3 mol·L–1 KCl) reference electrode. The pitting potential (E
pit) values, referred to this reference electrode, showed
an increase when SB and LDH–SB were used. The blank sample
presented an E
pit of 0.08 V, while the
samples containing SB and LDH–SB presented E
pit values of 0.50 and 0.36 V, respectively.