Abstract
Fabricating layered double hydroxides (LDHs) coatings intercalated with corrosion inhibitors is considered an effective strategy for improving the corrosion resistance of metal substrates. However, to our best knowledge, studies applying LDHs coatings modified with ionic liquids (ILs) as environmentally friendly corrosion inhibitors to corrosion protection of metals and alloys have not been reported. In this contribution, two kinds of MgAl-LDHs coatings modified with imidazolium based dicationic ILs, namely LDH-C-6(m(2)im)(2)-I and IL@LDH-C-6(m(2)im)(2)-I, were successfully prepared on AZ31B magnesium alloy. The LDH-C-6(m(2)im)(2)-I coating intercalated with C-6(m(2)im)(2)-I ionic liquid was synthesized by the co-precipitation method and hydrothermal treatment, followed by a facile immersion experiment in a dimethyl sulfoxide solution containing C-6(m(2)im)(2)-PF6 ionic liquid to produce the IL@LDH-C-6(m(2)im)(2)-I composite coating. The surface morphologies and anti-corrosion properties of the two MgAl-LDHs coatings immersed in 3.5 wt% NaCl solution were investigated. The present results reveal that the LDH-C-6(m(2)im)(2)-I coating exhibits a uniform and dense petal-like nanoflowers structure, while the IL@LDH-C-6(m(2)im)(2)-I composite coating contains a compact C-6(m(2)im)(2)-PF6 IL film and a lamellar-structured LDH-C-6(m(2)im)(2)-I, which provides a double corrosion protection to the Mg alloy. As a result, the corrosion current density of IL@LDH-C-6(m(2)im)(2)-I is only thirty-eighth of that of LDH-C-6(m(2)im)(2)-I and 4 orders of magnitude lower than that of bare AZ31B Mg alloy. More importantly, the surface of samples coated with IL@LDH-C-6(m(2)im)(2)-I is still compact without being destroyed after 168 h of immersion, which can be ascribed to the synergistic effect of excellent self-healing and durable corrosion resistance. This work opens a new way of preparing MgAl-LDHs coatings modified with ionic liquids to remarkably enhance the anti-corrosion performance of Mg alloys.
NSTL
Elsevier