Phosphate loaded layered double hydroxides for active corrosion protection of carbon steel

ABSTRACT

Layered double hydroxides (LDHs) can serve as corrosion inhibitor reservoirs. In the present work, hydrotalcite-like LDHs were synthesized and employed as host matrixes for the release of phosphate. The morphological and structural properties of the as-prepared LDH-PO₄ were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The PO₄^3- adsorption uptake was successfully confirmed by the XRD results. The corrosion resistance of the coating with LDH-PO₄ was investigated by electrochemical impedance spectroscopy (EIS), which was approximately 1 order of magnitude higher than that of the blank coating after immersion for 168 h. Results of the scanning Kelvin probe technique revealed that the potential of LDH-PO4 coating was higher and smoother than that of the blank coating after exposure to 0.5 M NaCl solution. This effect is attributed to the release of PO₄³⁻ that forms a phosphate protective film in the scratched region.

KEYWORDS:

• Layered double hydroxide
• alkyd coating
• scanning Kelvin probe (SKP)
• active corrosion protection
• phosphate

Acknowledgements

The authors are grateful to Luoyang Ship Material Research Institute for the financial support for this research work and permission to publish this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).