MICRO-ENCAPSULATION FOR CORROSION DETECTION AND CONTROL

Pitting can be one of the most dangerous forms of corrosion because it is difficult to anticipate and prevent, relatively difficult to detect, occurs very rapidly, and can penetrate a metal without a significant amount of weight loss. Failures of metals by pitting can occur very suddenly and can be catastrophic. One way of preventing these failures is with a coating that can detect and heal localized corrosion. This work describes the development of a smart coating that uses micro-encapsulation technology to detect and heal pitting corrosion in the early stages. The dual function of the microcapsules is triggered by the pH changes that occur when pits begin to form on the surface of a metal. The microcapsules are designed to respond to the pH changes by breaking and releasing their contents. The contents can be a localized corrosion healing agent to terminate the corrosion process or an indicator that signals its initiation. Corrosion indicator and corrosion inhibitor containing microcapsules were formed and incorporated into representative paint systems. Test panels of selected steels and aluminum alloys were painted using these paints. Testing of compatibility between the microcapsules and the different paint systems are in progress. Initial results with the microcapsule containing paints show the presence of visible color changes at induced corrosion sites.