Effect of NH4+Concentration on Corrosion Behavior of N80 Steel in CO2-saturated 3％NaCl Solutions
NH4Cl was one of the important factors causing corrosion of tubing steel in shale oil envi-ronment.Herewith,the effect of NH4+concentration on the corrosion behavior of N80 steel in 3％NaCl so-lution saturated with CO2 was studied by means of mass loss method,electrochemical methods,scan-ning electron microscope(SEM),3D profilometer,X-ray diffraction(XRD),and X-ray photoelectron spec-troscopy(XPS).The results showed that NH4+concentration had a dual effect on the corrosion rate of N80 steel,i.e.promoting and inhibiting the corrosion rate.When the NH4+concentration was 0～500 mg/L,the uniform corrosion rate of N80 steel increased with the increasing NH4+concentration,while in the NH4+con-centration range of 1000～2000 mg/L,the uniform corrosion rate of N80 steel decreased with the increas-ing NH4+concentration,however,the pitting corrosion rate showed a similar trend as the uniform corro-sion.When the NH4+concentration was 500 mg/L,the uniform corrosion rate and pitting corrosion rate of N80 steel were the highest.Competition adsorption occurred between NH4+and Cl-on the metal surface at NH4+concentrations≤500 mg/L,while NH4+adsorption inhibited corrosion when NH4+concentration ex-ceeded 500 mg/L.
N80 steelsaturated CO2 environmentNH4+corrosionNH4+absorption
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