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Influence of cerium ions and shelf‐life of hybrid solution as pretreatment for AA 2024 aluminum alloy on its anticorrosion performance
Author(s) -
BravoAnagua Ernesto,
Aoki Idalina Vieira
Publication year - 2016
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.5901
Subject(s) - cerium , hybrid material , dispersant , materials science , silane , tetraethyl orthosilicate , alloy , nuclear chemistry , dielectric spectroscopy , corrosion , dilution , polymerization , chemical engineering , electrochemistry , inorganic chemistry , chemistry , electrode , composite material , metallurgy , polymer , nanotechnology , physics , engineering , optics , thermodynamics , dispersion (optics)
This paper proposes the use of an organic–inorganic hybrid GPTMS/TEOS/ γ ‐APS film for pretreatment of AA2024 aluminum alloy and to study the influence of the presence of Ce (III) and Ce (IV) ions and ageing of the hybrid solution. The hybrid synthesis was based in TEOS (tetraethyl orthosilicate) as the inorganic precursor, GPTMS ( 3 ‐glicidoxypropyltrimethoxy silane) as monomer and coupling agent and γ ‐APS (gamma‐aminopropyltrimethoxysilane) as crosslinking promoter. 400 and 100 ppm of Ce (III) or Ce (IV) ions were added in the hydrolysis solution acidified with acetic acid and allowed to complete the reaction for 72 h. After hydrolysis, the mixture was diluted in the dilution ratios 1 : 3 or 1 : 4 before standing for 60 min polymerize. The hybrid film was applied on AA2024 specimens using a ‘dip‐coater’. The coated specimens were cured in an oven at 150 °C for 1 h. Hybrid films anticorrosion behavior was evaluated by electrochemical impedance spectroscopy and scanning vibrating electrode. It was concluded that the film containing Ce (III) or Ce (IV) ions imparts higher protection to substrate comparing with hybrid films without cerium ions. For short immersion times, hybrid films with Ce (IV) ions for both dilution ratios presented better protective properties. Hybrid film with Ce (III) at dilution ratios 1 : 4 and 1 : 3 presented better corrosion protection and self‐healing in 0.1 mol l ‐1 NaCl solution, and it was indeed better noticed when testing hybrid films after longer times of immersion in the electrolyte. Kinematic viscosity of the hybrid solution has slightly increased in the presence of Ce (IV) for longer shelf‐life. Hybrid film thickness increased for longer shelf‐life of the hybrid solution. Copyright © 2015 John Wiley & Sons, Ltd.