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

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.