Carbon Steel In Neutral Solutions Research Articles

Scanning electrochemical cell microscopy: A versatile method for highly localised corrosion related measurements on metal surfaces

The development of tools that can probe corrosion related phenomena at the (sub)microscale is recognized to be increasingly important in order to understand the surface structural factors (grain orientation, inclusions etc.) that control the (electro)chemical stability (corrosion susceptibility, pitting, passivity etc.) of metal surfaces. Herein we consider the application of scanning electrochemical cell microscopy (SECCM), a relatively new member of the electrochemical droplet cell (EDC) family, for corrosion research and demonstrate the power of this technique for resolving structure and activity at the (sub)microscale. Hundreds of spatially-resolved (2 μm droplet size) potentiodynamic polarization experiments have been carried out on the several hours timescale and correlated to complementary structural information from electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) in order to determine the effect of grain orientation and inclusions on electrochemical processes at low carbon steel in neutral solution (10 mM KNO3). Through this approach, it has been shown unequivocally that for the low index planes, anodic currents in the passive region (an indicator of corrosion susceptibility) are greatest on (101) planes compared to (100) and (111) planes. Furthermore, individual sub-micron MnS inclusions have been probed and shown to undergo active dissolution followed by rapid repassivation. This study demonstrates the high versatility of SECCM and the considerable potential of this technique for addressing structure-activity problems in corrosion and electromaterials science.

Polyvinyl Pyrrolidone as a Green Corrosion Inhibitor of Carbon Steel in Neutral Solutions Containing NaCl: Electrochemical and Thermodynamic Study

Polyvinyl Pyrrolidone as a Green Corrosion Inhibitor of Carbon Steel in Neutral Solutions Containing NaCl: Electrochemical and Thermodynamic Study

Numerical reconstruction of digital holograms for the study of pitting dynamic processes of the X70 carbon steel in NaCl solution

In this paper, a new image processing method to reconstruct digital holograms is proposed. After the digital holograms were recorded in situ during the electrochemical experiment, three-dimensional images were numerically reconstructed to study pitting dynamic processes of the X70 carbon steel in neutral solution containing chloride ions. Compared with the digital holograms, the reconstructed images can capture subtle changes more readily, therefore, more revealing. The radii of the pits were different, for they were induced at different times and propagated at different rates. It is expected that this method can be used extensively in studying the electrochemical dynamic processes at the electrode/electrolyte interface.

The effect of zinc‐to‐HEDP molar ratio on the effectiveness of zinc‐1, hydroxyethylidene‐1,1 diphosphonic acid in inhibiting corrosion of carbon steel in neutral solutions

PurposeThe aim of the present work was to study the synergistic effect of HEDP and zinc on inhibition of the corrosion of carbon steel in neutral oxygen‐containing chloride solutions, and to investigate the effect of zinc‐HEDP molar ratio on the effectiveness of the zinc‐HEDP inhibitive mixtures.Design/methodology/approachThe inhibition of the corrosion of carbon steel by zinc‐HEDP mixtures in neutral oxygen‐containing solutions was investigated in the presence of 0.003 M (106 ppm) chloride.FindingsIt was shown that the inhibition by these mixtures depended not only on the zinc/HEDP molar ratio but also on the concentration of both zinc and HEDP. HEDP concentration appeared to be crucial where good inhibition was not achieved at low concentrations and aggressive nature is observed at high HEDP levels. The effectiveness of the zinc‐HEDP mixtures enhanced inhibition by increasing the zinc content of the mixture, but the mechanism was only effective to a certain level, above which the inhibition effect declined. The predominant corrosion control mechanism of the zinc‐HEDP mixture was on the anodic (metal dissolution) reaction, but it also affected the rate and mechanism of the oxygen reduction reaction.Originality/valueDemonstrates how the effectiveness of the zinc‐HEDP mixtures can enhance inhibition by increasing the zinc content of the mixture.

The role of phosphonates as transporters of Zn2+ ions in the inhibition of carbon steel in neutral solutions containing chlorides

Phosphonates have shown synergistic effects in combination with Zn2+ ions in controlling the corrosion of carbon steel immersed in neutral aqueous environments containing 60‐ppm Cl‐. The role of phosphonates in the presence of Zn2+ ions has been investigated by polarisation tests and weight loss results. It was observed that the phosphonates functioned as transporters of Zn2+ ions from the bulk of the solution towards the metal surface. The phosphonate‐Zn2+ bond is sufficiently strong to carry Zn2+ ions from the bulk solution towards the metal surface, but is weak enough for them to break to form a phosphonate‐Fe2+ bond at anodic sites on the metal surface. Inhibition efficiency increases when the phosphonate‐Zn2+ complex remains in solution in soluble form. Inhibition efficiency decreased when the phosphonate‐Zn2+ complex was precipitated in the bulk of the solution.

Investigation of the Inhibitive Effect of N-Phosphono-Methyl-Glycine on the Corrosion of Carbon Steel in Neutral Solutions by Electrochemical Techniques

Abstract Steady-state current-voltage curves for various disk rotation rates were combined with electrochemical impedance measurements to investigate the corrosion inhibition of carbon steel by N-p...

Inhibition mechanism of carbon steel in neutral solution by N-phosphono-methyl-glycine

Corrosion inhibition of carbon steel in neutral aqueous solutions by N-phosphono-methylglycine (NPMG) is based mainly on the formation of an inhibiting film that protects the base metal. In order to understand the structure and composition, the layers formed on carbon steel were sputtered by an argon beam to obtain a depth profile using Auger electron spectroscopy (AES). The influence of changes in the water composition using model solutions (with and without calcium) in contact with carbon steel on the formation and growth rate of the film was studied. In addition, the effect of several factors such as time of contact and the addition of some cations, such as Ca 2+ and Zn 2+, on the formation and composition of the inhibiting films was investigated. In addition to surface analysis, weight loss method was used to optimize and characterize the inhibitor efficiency and the effect of synergism.