Effect of Nd³⁺ Ion Concentration on the Corrosion Resistance of API X70 Steel in Chloride‐Rich Environments

Abstract

In this study, the effect of the addition of Nd 3+ ions as a corrosion inhibitor of the API X70 steel in a medium rich in chlorides was evaluated. e performance of the Nd 3+ ions was evaluated by means of electrochemical techniques such as potentiodynamic polarization curves, open circuit potential measurements, linear polarization resistance, and electrochemical impedance spectroscopy, as well as by means of scanning electron microscopy and EDS measurements. e results showed that Nd 3+ ions reduce the corrosion rate of steel at concentrations as low as 0.001 M Nd 3+ . At higher concentrations, the inhibition efficiency was only slightly affected although the concentration of chloride ions was increased by the addition of the inhibitor. e adsorption of the Nd 3+ ions promotes the formation of a protective layer of oxides/hydroxides on the metal surface, thereby reducing the exchange rate of electrons. Nd 3+ ions act as a mixed inhibitor with a strong predominant cathodic effect.

Sustainable Development of Corrosion Inhibitors from Electronic Scrap: Synthesis and Electrochemical Performance

“…Electrochemical Evaluation. In order to compare the performance of the inhibitor synthesized from permanent magnets, its electrochemical evaluation was carried out in the same way as described by the authors in a previous work where neodymium chloride (analytical reagent, AR) was used as a corrosion inhibitor [24].…”

“…However, despite the fact that most studies have focused on compounds based on Ce and La [17][18][19][20][21][22][23], the use of neodymium salts can also be an alternative to mitigate the corrosion problems. In a recent study, the authors have reported that neodymium chloride has excellent corrosion inhibition efficiency for API X70 steel immersed in a chloride-rich solution [24].…”

Electrophoretic Deposition of Chitosan Films Doped with Nd2Ti2O7Nanoparticles as Protective Coatings against Corrosion in Saline Solutions

“…The observed changes allow inferring that the Figure 12: Equivalent circuit used to fit the impedance spectra. 8 International Journal of Polymer Science presence of the chitosan film decreases the dissolution rate of the carbon steel (increase in anodic slope), and due to the great displacement of the corrosion potential towards more active potentials (>200 mV), it acts as a cathodic coating affecting the oxygen reduction rate (cathodic reaction) and shifting the polarization curve to lower current densities [49]. The behavior of carbon steel coated with chitosan doped with nanoparticles is very similar to that observed in the presence of the undoped chitosan film.…”

“…In the case of corrosion inhibitors, it has been suggested that when they cause a displacement in OCP values greater than ±85 mV, with respect to the blank, they can be defined as anodic or cathodic inhibitors depending on the direction of displacement [49,[54][55][56]. Therefore, in this case, it can be assumed that the deposited chitosan films act as cathodic coating based on the displacement caused in the OCP values with respect to bare carbon steel.…”

“…In addition, it is not possible to define the low-frequency plateau which indicates that the charge transfer resistance R ct is greater than the last registered value. It is common that in the Nyquist diagram, the real time constants associated with the corrosion process are not observed; this is due to the fact that the first time constants generally evolve between the high-frequency region and the intermediate-frequency region, and in the Nyquist diagram, the most visible experimental data correspond to the low-frequency region [49,51].…”