Electrochemical and anticorrosion behaviors of hybrid functionalized graphite nano-platelets/tripolyphosphate in epoxy-coated carbon steel

• FGNP was combined with TPP to obtain a hybrid nano-particle.
• TEM image showed uniform distribution of the hybrid nanoparticles in epoxy coating.
• FGNP is a substrate for linking of TPP anions by hydrogen bonding.
• FGNP as an accelerator, provides rapid iron phosphate passive film formation.
• The hybrid nano-particle can provide long-term corrosion protection.

Functionalized graphite nano-platelets (FGNP) were combined with tripolyphosphate (TPP) to gain a hybrid nano-particle (FGNP-TPP) with homogenous dispersion in epoxy, resulting in an excellent anti-corrosion coating for carbon steel substrate. Characterization analyses of the hybrid nano-particle were performed by FT-IR, SEM, XRD and TEM. TPP was linked to FGNP nano-particles by hydrogen bondings. Different epoxy coatings formulated with 1 wt.% of FGNP, FGNP-TPP and TPP were evaluated. Electrochemical investigations, salt spray and pull-off tests showed that the hybrid nano-particle can provide long-term corrosion protection compared to FGNP and TPP due to synergistic effect between FGNP as an accelerator and TPP as a corrosion inhibitor to produce a uniform and stable iron-phosphate passive film with high surface coverage.

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