The Influence of Grain Size of Pure Iron Metal on Corrosion Inhibition in Presence of Sodium Nitrite

Abstract

The effects of grain size reduction on the corrosion inhibition of sodium nitrite were investigated using polarization curves and electrochemical impedance spectroscopy (EIS). Nanocrystalline iron (~ 45 nm) was produced by pulse electrodeposition using citric acid bath. The grain size of a nanocrystalline surface was analyzed by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM). The most intensive first-order peak (211) of the XRD patterns was taken for detailed analysis using a Gaussian fitting curve. The tests were carried out in 25 mg/l NaCl + 57 mg/l Na 2 SO 4 with different concentration of sodium nitrite aqueous solutions. The results revealed that due to the adsorption process which leads to the formation of a protective layer with a greater charge transfer resistance the inhibition effect and corrosion protection of sodium nitrite inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The standard free energy of adsorption (∆G ads ) revealed a strong interaction between inhibitor and nanocrystalline surface. This was attributed to the increased number of the active sites caused by nanocrystalline surface.

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“…Over the decades, different authors have postulated various methods for the synthesis and characterization of IONPs [ 61 – 65 ], including physical [ 66 ], chemical [ 67 ], or biological [ 68 ]. Recently, a few pieces of literature have attempted to combine two or more methods of the known conventional technique of synthesizing nanoparticles [ 69 – 72 ].…”

The corrosion inhibition effect of phytic acid on 20SiMn steel in saturated Ca(OH)2 solution with 1 mol L−1 NaCl

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