Characterization of Zn-Al-V ₁₀O ₂₈ ^6- corrosion-inhibiting hydrotalcite pigments in epoxy resins

In this study, a hydrotalcite-like compound containing Zn and Al host hydroxide layers with the decavanadate anion ([V ₁₀O ₂₈] ^6-) in the interlayer was synthesized and was used as a pigment in an epoxy resin for the corrosion inhibition of AA2024-T3 alloys. Corrosion inhibition and anion exchange with aggressive Cl ^- anions were characterized using a simulated scratch cell, potentiodynamic polarization, electrochemical impedance spectroscopy, inductively coupled plasma optical emission spectrometry, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Some useful comparisons were made with SrCrO ₄-pigmented primers using parameters like coating resistance, coating capacitance, water uptake and breakpoint frequency. Preliminary results indicate that hydrotalcite pigments provide substantial corrosion protection by anion exchange with Cl ^- ions and "self-healing" of the bare substrate. Osmotic blistering of these pigmented organic coatings applied to inert substrates was also studied. A critical solution concentration exists below which these primers blister.