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Title: Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions

Abstract

Electrochemical characteristics of Al 6061 (UNS A96061), Al and an Al-Cu alloy were investigated in aqueous solutions. Inhibition of the corrosion processes in basic solutions was studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. Among a series of inhibitors, molybdate (MoO{sub 4}{sup 2{minus}}) and dichromates (Cr{sub 2}O{sub 7}{sup 2{minus}}) were found effective in passivating the metal or alloy surface. The high inhibition action of Cr{sub 2}O{sub 7}{sup 2{minus}} was traced and discussed. X-ray photoelectron spectroscopy (XPS) of the different electrode materials revealed the presence of Cu peaks on the Al-Cu alloy surface. Immersion of the different electrodes in basic solutions containing the same concentration of Cr{sub 2}O{sub 7}{sup 2{minus}}, MoO{sub 4}{sup 2{minus}}, and sulfate (SO{sub 4}{sup 2{minus}}) anions did not show characteristic peaks of Cr, Mo, or S, which meant the surface layer consisted mainly of aluminum oxide (Al{sub 2}O{sub 3}). Depth profiling experiments up to 6.0-nm thickness showed the Cu peaks of the Al-Cu alloy appeared after etching and that Mo was incorporated in the surface film. The presence of Cu on the Al-Cu surface initiated flawed regions, identified by scanning electron microscopy, which were responsible for increased corrosion rates of this alloy. Effectiveness of the dichromate asmore » a corrosion inhibitor for these materials resulted from its powerful oxidizing properties, which led to formation of a stable passive film.« less

Authors:
;  [1]
  1. Univ. of Kuwait, Safat (Kuwait)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
669825
Resource Type:
Journal Article
Journal Name:
Corrosion
Additional Journal Information:
Journal Volume: 54; Journal Issue: 5; Other Information: PBD: May 1998
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CORROSION PROTECTION; ALUMINIUM; ALUMINIUM ALLOYS; COPPER ALLOYS; ELECTROCHEMISTRY; CORROSION INHIBITORS; AQUEOUS SOLUTIONS; FILMS; PASSIVATION; SPECTROSCOPY

Citation Formats

Al-Kharafi, F M, and Badawy, W A. Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions. United States: N. p., 1998. Web. doi:10.5006/1.3284865.
Al-Kharafi, F M, & Badawy, W A. Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions. United States. https://doi.org/10.5006/1.3284865
Al-Kharafi, F M, and Badawy, W A. 1998. "Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions". United States. https://doi.org/10.5006/1.3284865.
@article{osti_669825,
title = {Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions},
author = {Al-Kharafi, F M and Badawy, W A},
abstractNote = {Electrochemical characteristics of Al 6061 (UNS A96061), Al and an Al-Cu alloy were investigated in aqueous solutions. Inhibition of the corrosion processes in basic solutions was studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. Among a series of inhibitors, molybdate (MoO{sub 4}{sup 2{minus}}) and dichromates (Cr{sub 2}O{sub 7}{sup 2{minus}}) were found effective in passivating the metal or alloy surface. The high inhibition action of Cr{sub 2}O{sub 7}{sup 2{minus}} was traced and discussed. X-ray photoelectron spectroscopy (XPS) of the different electrode materials revealed the presence of Cu peaks on the Al-Cu alloy surface. Immersion of the different electrodes in basic solutions containing the same concentration of Cr{sub 2}O{sub 7}{sup 2{minus}}, MoO{sub 4}{sup 2{minus}}, and sulfate (SO{sub 4}{sup 2{minus}}) anions did not show characteristic peaks of Cr, Mo, or S, which meant the surface layer consisted mainly of aluminum oxide (Al{sub 2}O{sub 3}). Depth profiling experiments up to 6.0-nm thickness showed the Cu peaks of the Al-Cu alloy appeared after etching and that Mo was incorporated in the surface film. The presence of Cu on the Al-Cu surface initiated flawed regions, identified by scanning electron microscopy, which were responsible for increased corrosion rates of this alloy. Effectiveness of the dichromate as a corrosion inhibitor for these materials resulted from its powerful oxidizing properties, which led to formation of a stable passive film.},
doi = {10.5006/1.3284865},
url = {https://www.osti.gov/biblio/669825}, journal = {Corrosion},
number = 5,
volume = 54,
place = {United States},
year = {Fri May 01 00:00:00 EDT 1998},
month = {Fri May 01 00:00:00 EDT 1998}
}