resumo
The present work explores effects of shelf-life, temperature and the presence of cerium nitrate additive on the protective performance of sol-gel coatings applied on AA2024. These are important parameters when industrial applicability of coating formulations is considered. The studied sol-gel system is based on a combination of metalorganic precursor titanium(IV) propoxide and hybrid epoxy silane 3-glycidoxypropyltrimethoxysilane. The synthesized sol-gel formulations without or with addition of 0.007 M Ce(NO3)(3) were aged during different times at temperatures 25 degrees C or 6 degrees C. FTIR results show that the intensities of the bands associated to Si- O-Si increase with respect to Si-OH groups during the aging process as a result of extended condensation. However, such transformations occur less rapidly at low temperature. The electrochemical impedance spectroscopy measurements clearly show that sol-gel coatings corresponding to the sol-gel aged at low temperature exhibit similar corrosion protective capabilities compared to the coating obtained without sol-gel aging. It is also observed that the protection performance of the sol-gel coatings with cerium nitrate obtained after two weeks of sol-gel aging is lower compared to the coatings without cerium additive. This effect is attributed to the enhanced reactivity of the sol-gel due to cerium(III) presence. (C) 2014 Elsevier B.V. All rights reserved.
palavras-chave
CORROSION PROTECTION; CERIUM CONCENTRATION; CONVERSION COATINGS; ALUMINUM 2024-T3; ALLOYS; PERFORMANCE; INHIBITION; CONDENSATION; CAPACITANCE; CHROMATE
categoria
Materials Science; Physics
autores
Yasakau, KA; Carneiro, J; Zheludkevich, ML; Ferreira, MGS
nossos autores
Jorge Augusto Oliveira Carneiro
Bolseiro de pós-Doutoramento
Kiryl Yasakau
Investigador Auxiliar
Mário Guerreiro Silva Ferreira
Professor(a) Jubilado(a)
Mikhail Zheludkevich
Investigador Principal ConvidadoGrupos
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos
G4 - Materiais Renováveis e Economia Circular
agradecimentos
Authors acknowledge post-doctoral grant SFRH/BPD/80754/2011, Project no. 11474 - Sistema de incentivos a IDT: Projectos em co-promocao: QREN/FEDER, Pre-tratamentos Sol-gel NAnoesTruturados para Ligas de ALuminio Utilizadas em Aeronautica (NATAL); Dr. Andrei Salak is acknowledged for help with XRD analysis.