ABSTRACT

In this paper, several important aspects of selected papers in the emerging technology of smart coatings will be reviewed, and the application of selected principles to the problem of steel corrosion will be discussed.

INTRODUCTION

The corrosion that is often associated with offshore structures can lead to a loss in structural integrity as well as a reduction in service life. The corrosion properties of a metal with moderate corrosion resistance can be enhanced by coating it with a more corrosion resistant metal. Alternatively, the substrate metal may be coated with a non-metallic material that acts to restrict access to the metal, or a less corrosion resistant metal which will sacrifice itself in the protection of the substrate metal. In the case of the non-metallic material, it can simply act as a barrier, and in the latter case, the less corrosion resistant metal can corrode preferentially as in galvanized steel.

In recent years, it has become possible to impart additional life to the coating by incorporating chemical compounds or polymers. It has also become possible to obtain valuable information from the coating itself. These accomplishments have been achieved by using several coating principles that are relevant to corrosion sensing. These principles make use of a number of developments that include, but are not limited to the following: paint systems with color-changing compounds that respond to pH changes that result from corrosion processes; coating compounds that exhibit non-fluorescent to fluorescent states as a result of oxidation or other interactions with metal ions; the incorporation of color dyes into the coating in the form of dye-filled micro (or nano) capsules that release these dyes when the coating is damaged; and piezoelectric thin films that exhibit electrical changes as a result of mechanical deformation.

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