Fabrication and Characterization of PO₄³⁻Intercalated Zn-Al- Layered Double Hydroxide Nanocontainer

Abstract

Zn-Al-NO3− layered double hydroxide (LDH) nanocontainers loaded with PO43− anion with capability of releasing inhibitive species and absorbing corrosive chloride ions were successfully synthesized by an anion exchange route. The prepared nitrate based LDHs were well characterized by scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, thermalgravimetric-differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS). The inhibitive performance of the Zn-Al-PO43− LDH nanocontainer was investigated by electrochemical noise (EN) and surface analysis. Results revealed that Zn-Al-PO43− LDH nanocontainer can dramatically reduce the corrosion rate of mild steel through releasing inhibitive species i.e. phosphate anion and zinc cations and absorbing the chloride anions. Zn-Al-PO43− LDH nanocontainers were also incorporated into a silane film and then applied on mild steel. Finally, epoxy coating was applied on the steel samples without and with silane treatment. EN and field emission scanning electron microscope (FE-SEM) tests were performed on the sample to reveal its self-healing performance. Results showed enhanced active corrosion protection properties of silane film after addition of Zn-Al-PO43− LDH compared to Zn-Al-NO3− LDH. Zn-Al-PO43− LDH protected the defect site through forming a protective film. This self-healing co-delivery system has significant promise for the improvement of coating protection.