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inhibition of aa2024-t3 corrosion by vanadates

Metavanadates are predominant species at neutral pHs and mM concentrations at room temperature. . Introduction. . Decavanadate [V10O286-] ion made up of 10 VO6 octahedra. All vanadate monomers are tetrahedrally coordinated . . . H Guan and R Buchheit, Corrosion 60 (2004) p284.. AA2024-T3 in 0.124 M NaCl, pH 6.

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inhibition of aa2024-t3 corrosion by vanadates

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    1. Inhibition of AA2024-T3 Corrosion by Vanadates Mariano Iannuzzi and G. S. Frankel Fontana Corrosion Center Department of Materials Science and Engineering The Ohio State University Columbus, OH 43210 Also: T. Young (OSU Chemistry) and H. S. Isaacs Funded by AFOSR under award F 49620-02-0321 Maj. J. Gresham, PhD, contract monitor

    3. Effects of Acidification 150 mM NaVO3 solution (pH 8.8) injected into base solutions of varying pH and volume. Final pH independent of pH0 from pH0 3-10. Final solution was colored when initial pH < 4. It is not possible to lower pH without introducing color change. Colored solutions do not change color or become clear when pH is increased.

    4. Nuclear Magnetic Resonance (NMR) NMR gives high quality structural data NMR sensitive to the different vanadium oligomers Protonation/ deprotonation reactions can be detected by changes in chemical shift (CS) Vanadate speciation in varied aqueous environments is well characterized Integration of the signal gives quantitative information

    5. Effects of pH Adjustment

    6. Effects of [NaVO3] at pH 8.71

    7. Anodic Polarization Curves

    8. Cathodic Polarization Curves

    9. Chrono Amperometry on Cu

    10. Deaerated Solution

    11. XPS Analysis

    12. XANES Analysis

    13. Cathodic Polarization Curves

    14. Adsorption Isotherm

    15. Long Term Exposure

    16. Long Term Exposure

    17. Aging of V10 Solutions

    18. Effects of Aging V10 Solutions

    19. Effects of Solution pH

    20. Effects of Solution pH

    24. In situ AFM Scratching: 1 mM V1 As polished AA2024-T3

    25. In situ AFM Scratching: 1 mM V1

    26. Conclusions Vanadate monomers are not present in solutions containing decavanadates. The presence of V1 species is critical for corrosion protection. V1 is a potent inhibitor of O2 reduction. Decavanadates are not good inhibitors of corrosion and O2 reduction. Control of O2 reduction kinetics by V1 ? Adsorption mechanism? Decavanadates reduce at the surface after injection under potential control. Aging of high pH V10 solutions did not improve inhibition performance. [V1] increases with pH but has no extra beneficial effect on oxygen reduction rate. [V1] protects S phase particles, even during scratching Any coating system based on vanadates be able to release V1 to the damaged area.

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