Active protective treatments for galvanically coupled AA2024 and CFRP

Abstract

VII Abstract In the present work “smart” nanocontainers were synthesized in order to incorporate them into an organic coating and protect against corrosion of the aluminum alloy (AA2024) galvanically coupled with carbon fiber reinforced plastic (CFRP). The containers were loaded with organic (2-mercaptobenzothiazole and 1,2,3 – benzotriazole) and inorganic (metavanadate, tungstate and molybdate) inhibitors in the case of Mg/Al and Zn/Al LDH nanoreservoirs. In the case of the bentonite nanocontainers, the containers were loaded with Ce(NO3)3. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed in order to characterize the obtained nanocontainers. The nanocontainers were enbeded into epoxy coating on the surface of model multi-material system (AA2024 galvanically coupled with CFRP). The LDHs loaded with different inhibitors and combined with bentonite loaded with Ce3+, increase the anticorrosion protection properties of the coating. The analyses of the anticorrosion properties of the coatings were performed using zero resistance ammetry (ZRA), electrochemical impedance spectroscopy (EIS), optical microscopy, salt spray test (SST) and scanning vibrating electrode technique (SVET) measurements. The laboratory work was realized in University of Aveiro in collaboration with industrial environment of Airbus group.

No presente trabalho revestimentos "inteligentes" foram sintetizados com a finalidade de proteger contra a corrosão a liga de alumínio AA2024 acoplada galvanicamente com a fibra de carbono reforçado com plástico (CFRP). Os nanocontentores LDH Mg/Al LDH e Zn/Al LDH foram carregados com os inibidores orgânicos 2-mercaptobenzotiazole e 1,2,3-benzotriazole, e com inibidores inorgânicos metavanadato, tungstato e molibdato. No caso dos nanocontentores de bentonite o inibidor incorporado foi o Ce(NO3)3. A análise por difração de raios-X (DRX) e microscopia eletrónica de varrimento (MEV) foram realizadas a fim de caracterizar os nanocontentores obtidos. Os nanocontentores foram aplicados em revestimento epóxi na superfície do sistema modelo (AA2024 galvanicamente acoplado com CFRP), os LDH’s preenchidos com inibidores em mistura com Ce3+ carregado na bentonite foram usados com o objetivo de aumentar as propriedades de proteção do revestimento contra a corrosão. As análises das propriedades anticorrosivas dos revestimentos foram realizadas utilizando o ZRA (Zero resistance ammeter), espectroscopia de impedância eletroquímica (EIS), microscopia ótica, teste de nevoeiro salino (SST) e SVET (scanning vibrating electrode technique). O trabalho foi realizado em ambiente laboratorial e posteriormente em ambiente industrial (Airbus group).