Synergy between Galvanic Protection and Self-Healing Paints

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• 作者：Lance Michael Baird ; Marcia W. Patchan ; Melanie Morris ; Adam J. Maisano ; Terry E. Phillips ; Jason J. Benkoski ; Rengaswamy Srinivasan
• 刊名：Langmuir
• 出版年：2015
• 出版时间：September 29, 2015
• 年：2015
• 卷：31
• 期：38
• 页码：10610-10617
• 全文大小：525K
• ISSN：1520-5827

文摘

Painting is a cost-effective technique to delay the onset of corrosion in metals. However, the protection is only temporary, as corrosion begins once the coating becomes scratched. Thus, an increasingly common practice is to add microencapsulated chemical agents to paint in order to confer self-healing capabilities. The additive鈥檚 ability to protect the exposed surface from corrosion depends upon (i) how long the chemical agent takes to spread across the exposed metal; (ii) how long the agent takes to form an effective barrier layer; and (iii) what happens to the metal surface before the first two steps are complete. To understand this process, we first synthesized 23 卤 10 渭m polyurea microcapsules filled with octadecyltrimethoxysilane (OTS), a liquid self-healing agent, and added them to a primer rich in zinc, a cathodic protection agent. In response to coating damage, the microcapsules release OTS into the scratch and initiate the self-healing process. By combining electrochemical impedance spectroscopy, chronoamperometry, and linear polarization techniques, we monitored the progress of self-healing. The results demonstrate how on-demand chemical passivation works synergistically with the cathodic protection: zinc preserves the surface long enough for self-healing by OTS to reach completion, and OTS prolongs the lifetime of cathodic protection.