Acrylate-based hybrid sol-gel coating for corrosion protection of AA7075-T6 in aircraft applications : the effect of copolymerization time

Rodič, Peter (author), Cerc Korošec, Romana (author), Kapun, Barbara (author), Mertelj, Alenka (author), Milošev, Ingrid (author)

Pre-hydrolysed/condensed tetraethyl orthosilicate (TEOS) was added to a solution of methyl methacrylate (MMA) and 3-methacryloxypropyltrimethoxysilane (MAPTMS), and then copolymerised for various times to study the influence of the latter on the structure of hybrid sol-gel coatings as corrosion protection of aluminium alloy 7075-T6. The reactions taking place during preparation were characterised using real-time Fourier transform infrared spectroscopy, dynamic light scattering and gel permeation chromatography. The solution characteristics were evaluated, using viscosimetry, followed by measurements of thermal stability determined by thermogravimetric analysis. The optimal temperature for the condensation reaction was determined with the help of high-pressure differential scanning calorimetry. Once deposited on 7075-T6 substrates, the coatings were evaluated using a field emission scanning electron microscope coupled to an energy dispersive spectrometer to determine surface morphology, topography, composition and coating thickness. Corrosion properties were tested in dilute Harrison’s solution (3.5 g/L (NH$_4$)$_2$SO$_4$ and 0.5 g/L NaCl) using electrochemical impedance spectroscopy. The copolymerization of MMA and MAPTMS over 4 h was optimal for obtaining 1.4 µm thick coating with superior barrier protection against corrosion attack (|Z$_{10}$ $_{mHz}$| ~ 1 GΩ cm$^2$) during three months of exposure to the corrosive medium.

• Language: English
• Keywords: AA7075-T6, hybrid sol-gel, copolymerization, corrosion, dilute Harrison’s solution
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 26 str.
• Numbering: Vol. 12, iss. 4, art. 948
• PID: 20.500.12556/RUL-133729
• UDC: 620.1/.2
• ISSN on article: 2073-4360
• DOI: 10.3390/polym12040948
• COBISS.SI-ID: 33305639
• Publication date in RUL: 13.12.2021

Record is a part of a journal

• Title: Polymers
• Shortened title: Polymers
• Publisher: MDPI
• ISSN: 2073-4360
• COBISS.SI-ID: 517951257

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 19.04.2020