When 3:30 PM - 5:00 PM Feb 04, 2011
Where 1670 CSE
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Rudy Buchheit, Department of Materials Science and Engineering, Ohio State

Corrosion inhibition by vanadates: understanding inhibitor interaction with complex alloy microstructures and demonstration of delivery approaches using synthetic nanostructured ion-exchange compounds.

Vanadate compounds dissolved in aqueous solutions are powerful corrosion inhibitors for high strength aluminum alloys used in aerospace applications. These compounds act to stifle the oxygen reduction reaction, which in turn stops the corrosion cell process. The extent of inhibition is dependent on the nature of the vanadate species present in solution. Results from solution phase 51V nuclear magnetic resonance work show excellent corrosion inhibition in the presence of tetrahedrally coordinated forms of vanadate and poor corrosion inhibition when octahedrally coordinated forms predominate. These findings establish the conditions where useful levels of corrosion inhibition by vanadates can be expected. Microfocal Raman spectroscopy shows that vanadates act specifically at Cu-rich intermetallic particles found in 2024-T3. Results suggests that a complex bi-layered polyvanadate polymer forms on Cu-rich intermetallic particles presumably interfering with the process of oxygen reduction. Results from microelectrochemical cell experiments carried out on a range of intermetallic compounds that typify the constituent particles in the alloy have been used to quantify the extent to which the ORR is inhibited on a phase-by-phase basis. This powerful corrosion inhibitor can be functionalized for use in organic coating systems by synthesizing nanostructured vanadate-bearing hydrotalcite compound pigments. How these compounds store and release the inhibitor in a way that leads to high levels of corrosion protection in organic coating systems will be discussed. 

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