Robust corrosion protection of Ni-thiolate coordination polymer/Mg(OH)2 coating on magnesium alloy AZ31

Although magnesium alloys have been effectively used in industry, they have weak corrosion resistance. Herein, robust Ni-thiolate coordination polymer Mg(OH)(2) coatings were prepared by an oxidation-hydrolysis-coordination (OHC) strategy to make AZ31 magnesium alloy highly resistant to corrosion in 3.5 wt% NaCl solution. The OHC process includes three steps: I) oxidation of AZ31 to produce AZ31@MgO; II) hydrolysis of MgO to produce Mg(OH)(2), cation exchange between Mg(OH)(2) and Ni(II) to produce MgeNi LDH; III) coordination of Ni(OH)(2) fromMgeNi LDH by the 1,4-Benzenedithiol (BDT) ligand to produce LDH-BDT coatings. Potentiodynamic polarization, EIS, and in situ SRET in 3.5 wt% NaCl solution were used to assess the hybrid coating's anti-corrosion performance. Surprisingly, LDH-BDT coating achieves excellent corrosion inhibition performance (99.9999%) with the icorr of 1.926 x 10(-1)0 A cm(-2) which is six orders of magnitude lower than that of AZ31 substrate, this is due to the cooperative effect, such as the physical protection provided by thick LDH-BDT coatings and the hydrophobic properties of Ni(II)-BDT coordination polymers. This study provides fresh insight into the fabrication of Mg(OH)(2)-based coatings modified with Ni-thiolate complex to significantly improve Mg alloys' resistance to corrosion. (c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).