scholarly journals Effects of Sodium Phosphate and Sodium Nitrite on the Pitting Corrosion Process of X70 Carbon Steel in Sodium Chloride Solution

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5392
Author(s):  
Yongyan Zhu ◽  
Jiayi Ding ◽  
Jianli Zhang ◽  
Liang Li
Keyword(s):  
Sodium Chloride ◽  
Carbon Steel ◽  
Sodium Nitrite ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Sodium Phosphate ◽  
Sodium Chloride Solution ◽  
Electrochemical Impedance ◽  
Protective Oxide ◽  
Salt Film

In this paper, effects of sodium phosphate (Na3PO4) and sodium nitrite (NaNO2) on the pitting corrosion of X70 carbon steel in 0.10 mol/L NaCl solution were investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) method, scanning electron microscope (SEM) and scanning electrochemical microscope (SECM). The SECM equipment was used to observe the dynamic processes of the pitting corrosion in situ. Na3PO4 or NaNO2 in the sodium chloride solution decreased the local anodic dissolution and increased the pitting resistance of the specimen. By analysis and comparison, it can be concluded that the inhibition effect of Na3PO4 is mainly due to the formation of a salt film, while the corrosion inhibition of NaNO2 is principally attributed to a protective oxide film on the electrode surface.

THE INHIBITION EFFECT OF ZINC AND SILICATE IONS ON PITTING CORROSION INDUCED BY CERIUM(III) IONS OF CARBON STEEL IN SODIUM CHLORIDE SOLUTION

2020 ◽  
pp. 2050038
Author(s):  
QIONGWEI LI
Keyword(s):  
Sodium Chloride ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
In Situ Observation ◽  
Inhibition Effect ◽  
Synergistic Inhibition

Pitting corrosion of carbon steel in sodium chloride solution induced by Ce[Formula: see text] and the synergistic inhibition effects of Ce[Formula: see text] and Zn[Formula: see text]/SiO[Formula: see text] were investigated using in-situ observation and electrochemical methods. The results showed that the presence of Ce[Formula: see text] could result in severe pitting corrosion and a positive shift in the corrosion potential. It was found that individual Ce[Formula: see text], Zn[Formula: see text], or SiO[Formula: see text] had low inhibition efficiencies, whereas the combination of Ce[Formula: see text] and Zn[Formula: see text] or SiO[Formula: see text] proved to be highly effective in inhibiting the development of pits in two different ways and in enhancing the corrosion resistance. The pitting corrosion and inhibition mechanisms were discussed based on the results.

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