Sol-gel based organic-inoganic hybrid coatings for corrosion protection of aerospace aluminium alloy

Lakshmi, RV and Aruna, ST and Sampath, S (2021) Sol-gel based organic-inoganic hybrid coatings for corrosion protection of aerospace aluminium alloy. In: 32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021.

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Abstract

Aluminum alloy 2024 is the most commonly used aircraft alloy because of its high damage tolerance, relatively high tensile strength and high strength to weight ratio. These properties are achieved by appropriate alloying with copper and magnesium which, in addition to strengthening phases, form copper -and magnesium- containing constituent particles. However, the presence of these alloying elements makes the alloy susceptible to localized corrosion making it impossible to use it without prior application of a corrosion protection system. Historically, the corrosion protection systems are based on Cr(VI) compounds which are now restricted due to their carcinogenic nature. In this direction, extensive research is pursued on organic–inorganic hybrid silane coatings to replace the toxic Cr (VI) component. In the present study, silica alumina hybrid sol -gel coatings are developed and explored for anticorrosion properties using electrochemical techniques and industry - standard tests. Apart from the basic coating, co rrosion inhibitors are explored to impart active protection to the alloy. The ability of silica - alumina coating to act as reservoir for storage of inhibitors is investigated. The results confirm that coatings containing cerium nitrate inhibitor in an optimum concentration offer superior protection to the surface. X-ray photoelectron and Raman spectroscopy studies provide evidence for the migration of cerium ions from the coating. Improved corrosion protection is attributed to the combined effect of the barr ier nature of the coating and the corrosion inhibiting nature of Ce3+ ions. Further, the role of morphology of the inhibitor when used in the form of solid particles instead of salts is studied. The compatibility of the developed sol -gel layer with subsequ ent top layers of the paint system is also evaluated.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: AA 2024, Cerium, Corrosion, Inhibitor, Sol-gel
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
CHEMISTRY AND MATERIALS > Metals and Metallic Materials
Depositing User: Smt Bhagya Rekha KA
Date Deposited: 28 Nov 2022 15:09
Last Modified: 28 Nov 2022 15:09
URI: http://nal-ir.nal.res.in/id/eprint/13789

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