The effects of thioureido imidazoline and NaNO2 on passivation and pitting corrosion of X70 steel in acidic NaCl solution. (15th May 2017)

• Record Type: Journal Article
• Authors: Zuo, Yu; Yang, Li; Tan, Yongjun; Wang, Yishan; Zhao, Jingmao
• Is Part Of: Corrosion science. Volume 120(2017)
• Page Start: 99
• Page End: 106
• Publication Date: 2017-05-15
• Subjects: A. Carbon steel -- B. Polarization -- B. XPS -- C. Pitting corrosion -- C. Passivation; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2016.12.015
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: In acidic NaCl + NaNO2 solution, addition of TAI promotes both passivation and pitting of X70 steel. The decreased pitting resistance is attributed to preferential adsorption of residue TU monomers. With extended immersion time, the pitting resistance increases to the original value without TAI. A multi-layer film with thiourea rich in inner and imidazoline rich in outer formed on surface. Inhibition effects of NaNO2 and TAI on steel are both superimposed and interactive. Abstract: The effects of thioureido imidazoline and NaNO2 on passivation and pitting corrosion of X70 steel in acidic NaCl solution were studied. The addition of thioureido imidazoline promoted passivation of the steel in the NaCl-NaNO2 solution, but the pitting potential decreased, which was attributed to the preferential adsorption of residue thiourea monomers in the inhibitor. With longer immersion time, the pitting potential in solution with thioureido imidazoline + NaNO2 increased to the value with only NaNO2 . A multi-layer film formed with thiourea rich in inner and imidazoline rich in outer. The compounded inhibition effect of thioureido imidazoline and NaNO2 was discussed.