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Corrosion control of aluminum and 6063 aluminum alloy in phosphoric acid and sodium hydroxide medium with some plant extracts

Prabhu, Deepa (2015) Corrosion control of aluminum and 6063 aluminum alloy in phosphoric acid and sodium hydroxide medium with some plant extracts. Phd. Thesis thesis, Manipal Institute of Technology, Manipal.

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Abstract

The work undertaken for the present investigation is an attempt to introduce Garcinia indica Choisy Extract (GIE), Terminalia chebula Ritz Extract (TCE) and Coriandrum sativum L. Extract (CSE) as green corrosion inhibitors for the corrosion control of aluminum and 6063 aluminum alloy in phosphoric acid and sodium hydroxide medium. Corrosion inhibition study of aluminum and 6063 aluminum alloy in phosphoric acid medium was done by potentiodynamic polarization method and electrochemical impedance spectroscopy technique. In sodium hydroxide medium, techniques employed were weight loss method and potentiodynamic polarization method. The surface morphology was studied in the absence and in the presence of inhibitors using scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX). Kinetic and thermodynamic parameters for the corrosion and inhibition processes were calculated and discussed in detail. Interaction between the material and the inhibitors was confirmed by fitting the results into appropriate adsorption isotherms. A suitable mechanism was proposed for the corrosion and corrosion inhibition process. All the studied plant products emerged as good corrosion inhibitors. The inhibition efficiency observed was more than 90 % in phosphoric acid medium and more than 80 % in sodium hydroxide medium for both aluminum and 6063 aluminum alloy. Mechanism of adsorption was through chemical adsorption process for GIE, whereas TCE and CSE underwent physical adsorption. Results obtained by different techniques were found to be in good agreement with one another. Use of green corrosion inhibitors are of importance because of their environmental and economic benefits.

Item Type: Thesis (Phd. Thesis)
Uncontrolled Keywords: Aluminum, 6063 aluminum alloy, phosphoric acid, sodium hydroxide, green inhibitors, potentiodynamic polarization technique, weight loss method, electrochemical impedance technique, SEM-EDX, physical and chemical adsorption
Subjects: Applied Science > ICAS Manipal
Engineering > MIT Manipal > Chemistry
Depositing User: MIT Library
Date Deposited: 23 Mar 2016 08:57
Last Modified: 23 Mar 2016 08:57
URI: http://eprints.manipal.edu/id/eprint/145623

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