Manipulating transport paths of inhibitor pigments

The microstructure of an organic coating affects the leaching of inhibitor pigment. And this microstructure can be manipulated by the addition of other pigments.

A laboratory scene.
The addition of ceria with a content of 5 wt% was the most effective to enhance hydrophobicity. Image source: totojang1977 (symbol image)

Adequate leaching of active inhibitor pigments in organic coatings is essential for corrosion protection that relies on active inhibition of the metallic substrate. Therefore, it is important to obtain a comprehensive understanding of the factors that influence leaching kinetics and mechanisms. In the present study, model organic coatings were formulated to investigate the influence of additional pigmentation (i.e. pigments other than the main inhibitor) on the leaching of species released from the main inhibitor pigment.

Increased leaching rate

It is found that addition of soluble/sparingly soluble pigments into the organic coating results in increased leaching rate. This is attributed to the formation of clusters comprised of both the main inhibitor pigment and the additional pigment. The network of cavities and voids formed upon dissolution and removal of the soluble pigment introduces transport paths in the organic coating, and consequently, facilitates the leaching of the main inhibitor pigment.

The study has been published in Progress in Organic Coatings, Volume 172, November 2022.

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