Corrosion protection of AA2024 by sol–gel coatings modified with MBT-loaded polyurea microcapsules

Abstract

In this work we report the synthesis of polyurea microcapsules loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) for corrosion protection of 2024 aluminum alloy. The microcapsules were prepared by interfacial polycondensation. The resulting capsules exhibit spherical shape, with diameter ranging between 100 nm and 2 µm. The loading content of MBT was found to be 5 wt% and release studies showed that MBT is preferentially released under acidic and alkaline conditions and follows the Fickian diffusion model. This pH dependency seems suitable for protection of metallic alloys where corrosion processes are accompanied by local pH changes. Furthermore, the microcapsules were added to a hybrid sol-gel coating and its performance assessed by electrochemical and accelerated standard tests. The results obtained indicate that capsules loaded with MBT do not affect negatively the barrier properties of sol-gel coatings, and contribute for the enhancement of adhesion of coatings to the metallic substrate. More relevant, these additives impart active corrosion protection suppressing corrosion activity at defect sites, which opens prospects for application of polyurea microcapsules as additives for high-performance coatings.

Hybrid Sol-Gel Coatings: Smart and Green Materials for Corrosion Mitigation

“…According to the authors, this coating system was developed aiming to be employed either as a complete corrosion protection system without a top coat or as primer for successive application of water-based top-coats. Recently, Ferreira et al [147] reported the synthesis of polyurea microcapsules loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) for corrosion protection of 2024 aluminum alloy. The microcapsules were prepared by interfacial polycondensation and added to a hybrid sol-gel coating.…”

Inhibition of mild steel corrosion in CO2 and H2S‐saturated acidic media by a new polyurea‐based material

“…Polyurea belongs to a class of organic polymers commonly used as protective coatings against metallic corrosion primarily due to their high thermal and chemical resistance, good abrasion resistance, molecular structure enhancement, waterproofing, and structural diversity . A number of studies on the corrosion inhibitive performance of polyurea coatings have been reported . The majority of these studies reported the utilization of polyurea derivatives as a coating for metallic structures primarily due to their lack of solubility in aqueous medium.…”

Production of Polymer Particles Loaded with Corrosion Inhibitor for Applications in Oil Wells

“…Latnikova studied the production of microcapsules through interfacial polymerization loaded with corrosion inhibitors for manufacture of self‐healing anticorrosion coatings. Maia et al manufactured pH‐sensitive polyurea microcapsules loaded with 2‐mercaptobenzothiazole (MBT) by interfacial polycondensation to mitigate corrosion in 2024 aluminum alloys. Feng and Cheng produced nanoparticles loaded with benzotriazole (BTA) for manufacture of intelligent coatings intended to protect steel pipelines from chloride solutions.…”