Synthesis of Inhibitor Nanocontainers with Two-Dimensional Structure and Their Anticorrosion Action in Sol-Gel Coating on AA2024-T3 Aluminum Alloy

Abstract

The synthesis of inhibitor nanocontainers with two-dimensional (2D) structure using graphene oxide and layered double hydroxides (GO/LDHs) via a coprecipitation method was studied. The corrosion inhibitors of vanadate anions (VOx−) and 2-mercaptobenzothiazole anions (MBT−) were loaded into the GO/LDHs nanocontainers by an anion exchange reaction and the products retained the 2D structure. GO/LDHs loaded with VOx− (GO/LDHs-VOx−) were added into a sol-gel coating on AA2024-T3. It was found that the corrosion protection of the sol-gel coating was effectively enhanced. No serious corrosion was observed on the alloy after 240 h of salt spray test. The enhancement of the protective properties was attributed to two aspects: the improvement of the barrier property from the good dispersion of the additive with the 2D structure and the good barrier of GO sheets, and the corrosion inhibition of vanadate anions. In other words, the protection mechanism was that GO/LDHs-VOx− provided the coating active and improved passive protection simultaneously.

Improvement of Corrosion Protection of Coating System via Inhibitor Response Order

“…Immersed in the 0.05 M NaCl solution, the substrate is extensively corroded, companying with large corrosion pittings and the deposition of corrosion products. After the addition of GO/LDHs-MBT, the quantity and size of pittings are obviously reduced, and two visible regions are presented (region A and B) [17,21]. In the case of GO/LDHs-VO x , the surface shows slightly changed and no evident pittings.…”

“…Nanocontainers GO/LDHs were prepared and encapsulated inhibitors, as described in our previous work [17]. In short, the nanocontainers GO/LDHs composed of GO and LDHs was synthesized via a co-precipitation method, and then loaded with inhibitors 2-mercaptobenzothiazole (GO/LDHs-MBT) and vanadate (GO/LDHs-VO x ) via anion exchange reaction.…”

“…The cleaned samples were coated with a sol-gel coating and then an epoxy coating. The sol solution formulation and coating preparation were described in detail elsewhere [17]. Briefly, nanofillers (GO/LDHs-MBT or GO/LDHs-VO x ) were dispersed in aqueous solution by stirring and sonication.…”

“…In our previous work, we characterized the morphology and structure of the GO/LDHs in detail [17]. Briefly, the GO/LDHs display characteristic diffractions of hydrotalcite-like materials [20], indicating the existence of LDHs (Figure 2a).…”

“…They influence thermal, mechanical, electrical, and functional properties of numerous coating systems [14][15][16]. In our recent study, it was shown that graphene oxide/layered double hydroxides (GO/LDHs) were able to encapsulate inhibitors MBT and vanadate by anion exchange reaction [17]. When incorporated into coatings, GO/LDHs showed good dispersion and controlled the release of inhibitors, which enhanced the corrosion protection properties of the coating.…”