Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel
Composite coatings prepared by mixing 5 wt.% polyaniline with commercial alkyd-based paints were applied on carbon steel. The polyaniline emeraldine chloride salt was prepared by procedure recommended by IUPAC, including deprotonation by ammonia hydroxide, and reprotonation with sulfamic, succinic,...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-07-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/13/8/1364 |
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| author | Branimir N. Grgur Aleksandra S. Popović Ayad Salem |
| author_facet | Branimir N. Grgur Aleksandra S. Popović Ayad Salem |
| author_sort | Branimir N. Grgur |
| collection | DOAJ |
| description | Composite coatings prepared by mixing 5 wt.% polyaniline with commercial alkyd-based paints were applied on carbon steel. The polyaniline emeraldine chloride salt was prepared by procedure recommended by IUPAC, including deprotonation by ammonia hydroxide, and reprotonation with sulfamic, succinic, citric, and acetic acids with different doping degrees or oxidation states. The steel samples with base and composite coatings were immersed in 3% NaCl and the corrosion current density was determined after 96 h in situ using the ASTM 1,10-phenanthroline method. The samples were also inspected by optical microscopy. It was shown that the composite coatings reduced the possibility of blister formations and delamination. The corrosion current density and the appearance of the corrosion products, whose area was determined by ImageJ software, closely followed the initial oxidation state of the polyaniline. It was also shown that damaged composite coatings with higher degrees of oxidized (doped) polyaniline were more prone to formation of corrosion products. The role of the initial state of the polyaniline is discussed. It is suggested that such behavior could be connected to the oxygen reduction reaction mechanism that proceeds mainly via two electron paths on the polyaniline particles, releasing a much smaller amount of hydroxyl ions, which is responsible for the delamination and blister formation of the commercial coatings. |
| first_indexed | 2024-03-10T23:44:18Z |
| format | Article |
| id | doaj.art-1771517b25c249e5b2336fcbb74268ec |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T23:44:18Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-1771517b25c249e5b2336fcbb74268ec2023-11-19T02:10:06ZengMDPI AGMetals2075-47012023-07-01138136410.3390/met13081364Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild SteelBranimir N. Grgur0Aleksandra S. Popović1Ayad Salem2Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11020 Belgrade, SerbiaFaculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11020 Belgrade, SerbiaFaculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11020 Belgrade, SerbiaComposite coatings prepared by mixing 5 wt.% polyaniline with commercial alkyd-based paints were applied on carbon steel. The polyaniline emeraldine chloride salt was prepared by procedure recommended by IUPAC, including deprotonation by ammonia hydroxide, and reprotonation with sulfamic, succinic, citric, and acetic acids with different doping degrees or oxidation states. The steel samples with base and composite coatings were immersed in 3% NaCl and the corrosion current density was determined after 96 h in situ using the ASTM 1,10-phenanthroline method. The samples were also inspected by optical microscopy. It was shown that the composite coatings reduced the possibility of blister formations and delamination. The corrosion current density and the appearance of the corrosion products, whose area was determined by ImageJ software, closely followed the initial oxidation state of the polyaniline. It was also shown that damaged composite coatings with higher degrees of oxidized (doped) polyaniline were more prone to formation of corrosion products. The role of the initial state of the polyaniline is discussed. It is suggested that such behavior could be connected to the oxygen reduction reaction mechanism that proceeds mainly via two electron paths on the polyaniline particles, releasing a much smaller amount of hydroxyl ions, which is responsible for the delamination and blister formation of the commercial coatings.https://www.mdpi.com/2075-4701/13/8/1364phenanthroline methodreprotonationdelaminationblisteringprotection mechanism |
| spellingShingle | Branimir N. Grgur Aleksandra S. Popović Ayad Salem Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel Metals phenanthroline method reprotonation delamination blistering protection mechanism |
| title | Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel |
| title_full | Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel |
| title_fullStr | Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel |
| title_full_unstemmed | Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel |
| title_short | Influence of Alkyd Composite Coatings with Polyaniline Doped with Different Organic Acids on the Corrosion of Mild Steel |
| title_sort | influence of alkyd composite coatings with polyaniline doped with different organic acids on the corrosion of mild steel |
| topic | phenanthroline method reprotonation delamination blistering protection mechanism |
| url | https://www.mdpi.com/2075-4701/13/8/1364 |
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