Pigmented epoxy coatings exposure

Corrosion inhibitors in paints protect metallic surfaces from oxidation. Coating primers are used when there is continuous exposure to corrosive elements, e.g., in marine applications. Examples are coal-tar derivatives, epoxy resins and coal-tar modified epoxies. Primers that inhibit corrosion by anodic or cathodic polarization contain inorganic metallic pigments such as chromates or leads or both. Composite pigments containing calcium oxide, zinc, silica, and oxides of phosphorus and boron can also be used (Mathias 1984). Nowadays, powder paints such as polyester and epoxy powder paints can also be used for corrosion inhibition (Rose and Vance 1997). 

Fig. 49. Corrosion ratings for 2014 Al alloy panels coated with an epoxy polyamide paint containing various pigments, after exposure to three different NaCl environments. The higher ratings indicate a poor performance. (After Baldwin et al. 1990.)...

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