posted on 2024-01-11, 14:06authored byXifang Chen, Xiaoyu Wu, Kai Zhang, Tao Long
In response to the poor anticorrosion properties of waterborne
coatings, g-C3N4 coated with
zinc phosphate and polyaniline (PANI) was synthesized by in situ polymerization.
Added to water-based epoxy-acrylate (WEP) emulsions, this new composite
is used as an anticorrosive agent to protect metal substrates. The
PANI film on the surface of g-C3N4 (denoted as CA) guarantees excellent g-C3N4 dispersion owing to the hydrophilic groups.
The addition of zinc phosphate was to improve the corrosion protection
ability of the composite (denoted as CAZP). The structure and chemical
composition of the CAZP composite were analyzed by X-ray diffraction,
Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy.
Transmission electron microscopy was used to monitor the morphological
changes of the composites and scanning electron microscopy to characterize
the topography of different coatings. By applying these analyses,
the successful formation of CAZP was confirmed. The anticorrosion
performance of g-C3N4, CA,
and CAZP coatings on Q235 carbon steel in 3.5 wt % NaCl solution was
evaluated by electrochemical impedance spectroscopy and dynamic potential
polarization curves. The results show that even after prolonged immersion
(60 days) in the NaCl solution, the |Z0.01Hz| of CAZP/WEP was still as high as 1.69 × 109 Ω·cm2. The corrosion rate was reduced to 9.590 × 10–6 mpy, 3 orders of magnitude lower than that of the blank coating.
This indicates that CAZP/WEP has excellent corrosion protection properties.