PO43--Loaded ZIF-8-type Metal-Organic Framework-Decorated Multiwalled Carbon Nanotube Synthesis and Application in Silane Coatings for Achieving a Smart Corrosion Protection Performance

In this research study, interfacial assembled nano-porous zeolitic imidazolate framework (ZIF-8) multiwalled oxidized carbon nanotubes (MW-OCNTs) were developed and introduced into a silane coating. To analyze the destructive behavior of the nanoparticles exposed to salty solutions with three distinctive pHs of 2, 7.5, and 12, various types of tests such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma (ICP) were accomplished. The XRD test revealed that the main characteristic peaks of ZIF-8 were eliminated and/or their intensity decreased. In accordance with the obtained data from the XRD test, nanoparticles at pH = 2 had been destructed more than those in the other two pHs. This result has been strongly confirmed by FESEM and ICP tests. The polarization test was employed to consider the active property of the synthesized nanoparticles. By utilizing the Tafel extrapolation method, corrosion parameters were obtained, and regarding the acquired data, the current density (icorr) of the salty solution including MW-OCNT@ZIF-8-Phosphate extract (1.45 mu A/cm2) was comparatively much lower than that of the blank sample (8.02 mu A/cm2). Meanwhile, the total resistance of bare steel immersed in the saline solution consisting of nanoparticle extract is 10,261.58 omega cm(2) while this magnitude for the blank sample is just 942.2 omega cm(2) after 120 h of immersion time. Electrochemical impedance spectroscopy inspection was applied to the reinforced intact coatings to scrutinize their passive/active inhibition efficiency. Surprisingly, the obtained results from Nyquist diagrams indicated that the total resistance for the coating reinforced by silanized MW-OCNT@ZIF-8-Phosphate reached 128,630 omega cm(2) after 48 h, which is noticeably greater than the magnitudes for the blank sample (57,784 omega cm(2)) and the coating including silanized MW-OCNT-ZIF-8 (97,320 omega cm(2)).