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Many potential corrosion inhibitors, such as cerium and molybdenum, have been examined in an effort to find a suitable replacement for hexavalent chromium. Additionally, microencapsulation of inhibitors has been suggested as a method that allows for the release of these water-soluble agents on-demand at the needed location. In this work, microcapsules sensitive to local variations in pH, which occur during the corrosion process, were loaded with cerium and molybdenum. The microcapsules were incorporated into a coating to determine their efficacy as a “smart coating” when utilized in this manner.
The coating system consisted of a standard epoxy with the incorporated microcapsules on aluminum alloy 2024-T3 and carbon steel (CRS) panels. The minimum Pigment Volume Concentration (PVC) required for corrosion protection was determined for each inhibitor. This determination was made utilizing Electrochemical Impedance Spectroscopy (EIS), Scanning Vibrating Electrode Technique (SVET), and accelerated weathering techniques. To determine how the coating properties were affected by the rupture of the microcapsules, the coatings were tested via Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) before and after release of the microcapsule contents. Localized EIS and SVET were used to determine the reaching power of the inhibitors’ effectiveness. Finally, the encapsulated inhibitors were also examined in conjunction with each other to examine any potential synergies that may develop.
The coating system consisted of a standard epoxy with the incorporated microcapsules on aluminum alloy 2024-T3 and carbon steel (CRS) panels. The minimum Pigment Volume Concentration (PVC) required for corrosion protection was determined for each inhibitor. This determination was made utilizing Electrochemical Impedance Spectroscopy (EIS), Scanning Vibrating Electrode Technique (SVET), and accelerated weathering techniques. To determine how the coating properties were affected by the rupture of the microcapsules, the coatings were tested via Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) before and after release of the microcapsule contents. Localized EIS and SVET were used to determine the reaching power of the inhibitors’ effectiveness. Finally, the encapsulated inhibitors were also examined in conjunction with each other to examine any potential synergies that may develop.