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


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 mu m. 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 a 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. (C) 2015 Elsevier B.V. All rights reserved.






Maia, F; Yasakau, KA; Carneiro, J; Kallip, S; Tedim, J; Henriques, T; Cabral, A; Venancio, J; Zheludkevich, ML; Ferreira, MGS

nossos autores


This work was developed in the scope of the project CICECO - Aveiro Institute of Materials (Ref. FCT UID /CTM /50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement and under the frame of NATAL Project Ref: 11474 Adi/ QREN/FEDER.; Dr. Igor Bdikin is greatly acknowledged for the provided help with mechanical properties measurements. FM, KY, SK and JT thank FCT for PhD SFRH/BD/72663/2010, Post-Doctoral SFRH/BPD/80754/2011, and Researcher IF/00856/2013 and IF/00347/2013 grants, respectively.

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