Protective coatings for AA 2024 based on cyclotetrasiloxane and various alkoxysilanes

[Display omitted] •Alkoxysilyl-functionalised tetracyclosiloxane precursor was synthesized.•Influence of various trialkoxysilane additives on protection effectivenes was tested.•Difference in short and long time scale testing was evaluated using EIS.•In situ Raman was used to follow formation of pit...

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Bibliographic Details
Published in:Corrosion science 2017-09, Vol.126, p.55-68
Main Authors: Rodošek, Mirjana, Koželj, Matjaž, Slemenik Perše, Lidija, Cerc Korošec, Romana, Gaberšček, Miran, Surca, Angelja Kjara
Format: Article
Language:English
Subjects:
Alkoxysilanes
Alloy
Aluminium
Anodic polarization
Crosslinking
Ethane
IR spectroscopy
NMR
Nuclear magnetic resonance
Polymer coatings
Protective coatings
Raman spectroscopy
Reflection
Spectrum analysis
Studies
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Summary:[Display omitted] •Alkoxysilyl-functionalised tetracyclosiloxane precursor was synthesized.•Influence of various trialkoxysilane additives on protection effectivenes was tested.•Difference in short and long time scale testing was evaluated using EIS.•In situ Raman was used to follow formation of pit.•Ex situ IR RA showed hydration and breakage of some siloxane bonds. An alkoxysilyl-functionalised precursor, 1,3,5,7-tetramethyl-1,3,5,7-tetra-(2-(3-trimethoxysilyl)propylsulfanyl)ethyl-cyclotetrasiloxane was synthesized to produce protective coatings. The addition of bis-end-capped 1,2-bis(trimethoxysilyl)ethane and various alkoxysilanes led to formation of more crosslinked coatings as evidenced by 29Si NMR and IR reflection-absorption spectroscopy. The structural changes during forced anodic polarization were followed using ex situ IR reflection-absorption and in situ Raman spectroelectrochemistry. The former technique shows hydration of coatings and cleavage of some siloxane bonds. In situ Raman bands revealed decrease in intensity, while imaging enabled to follow pit formation. The potentiodynamic polarization, impedance spectroscopy and exposure in salt chamber showed that coating with hexadecyltrimethoxysilane is the most efficient.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2017.06.011