The non-crystalline metal-organic framework for corrosion inhibitor behavior in sodium chloride solution

Abstract

The metal-organic frameworks (MOFs), namely ZIF-62, have the ligand of imidazole and benzimidazole, which are effective corrosion inhibitors. In this context, ZIF-62 is an ideal candidate in marine corrosion protection. However, it is not reported till present. Here, the non-crystalline ZIF-62 ( g -ZIF-62), a novel corrosion inhibitor carrier, is developed by melting the ZIF-62 crystal ( c -ZIF-62) and its corrosion inhibition performance on AZ91 Mg alloy is investigated by electrochemical measurement. The results show that ZIF-62 could effectively inhibit the Mg alloy from corrosion. More significantly, g -ZIF-62 shows a better corrosion inhibition effect, and the corrosion inhibition efficiency ( η ) is up to 83.6%. The glassy grain boundaries of g -ZIF-62 disappear when melting the c -ZIF-62, which hinders the invasion of corrosive media, e.g. H 2 O molecules, Na + and Cl − , to improve the stability in seawater. More importantly, the molar ratio of imidazole to benzimidazole is adjusted by the reaction time ( T m ). Given the significant steric hindrance, the much content of benzimidazole in g -ZIF-62(48 h) have high viscosity under T m , leading to the formation of a pyknotic glass for the corrosion inhibitors. Thus, this study not only highlights the potential of ZIF-62 as a corrosion inhibitor, but also provides fresh insights for the application of non-crystalline MOF in harsh seawater corrosion. • Corrosion inhibitor for metal–organic frameworks is reported. • The stability of MOFs in sodium chloride solution was improved by amorphous method. • The effect of synthesis time and corrosion mechanism were investigated. • ZIF-62 is used for the first time as corrosion inhibitor on the surface of AZ91 Mg alloy.