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Zinc-free pigment effects disbondment of epoxy-polyamide coating
Time: 2014-05-08 Source from: european-coatings
In the field of protective coatings, zinc-free pigments are proposed as promising anticorrosion compounds due to their excellent environmentally-friendly profile.
In a paper, researchers investigated the cathodic disbonding performance of a solvent-borne epoxy primer incorporating strontium aluminum polyphosphate (SAPP) as a zinc-free phosphate-based anticorrosion pigment.
SAPP improves resistance to cathodic disbonding
Regardless of the applied potential, the presence of SAPP in the coating formulation caused slower growth of the delamination area in comparison to ZP. According to the data obtained from EIS and SEM/EDX, this behaviour was attributed to locally controlled pH and the precipitated film restricting active zones available for electrochemical reactions.