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Tuesday, December 4, 2007 - 8:30 AM
Understanding Reactive Pigments for Cathodic Protection's Impact on Water Transport in Coatings
Corrosion of metallic components is often delayed by the use of protective coatings, and one class of corrosion defense used is cathodic protection. Cathodic protection on steel is regularly achieved by incorporating zinc pigments into the coating polymer binder, and similar methodology is under investigation to use magnesium on aluminum alloys. Understanding the protective ability of the coating as a function of time in an environment will help optimize coating design, and EIS offers one avenue to continuously monitor the status of a coating.
Model coatings made with zinc dust at various PVCs in an epoxy primer are compared and simulated. This comparison is based on measurements of single frequency temporal spectra along with periodic EIS frequency spectra and interpretation is aided by finite element analysis. How the kinetic parameters (diffusion coefficient, for example) and materials properties (relative dielectric coefficient, for example) are used to produce simulations will also be discussed. The use of room temperature ionic liquids as a means to measure normally inaccessible materials parameters will also be shown.