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The electrochemical behavior of copper and zinc in neutral (рН 7.4) borate buffer solution with addition of 0.5 M NaCl and the effect of 2-merсaptobenzothiazole (MBT) on the electrochemical processes and adsorption on these metals has been studied by means of electrochemistry and X-ray photoelectron spectroscopy (XPS). The formation of MBTmetal cation complex films on copper and zinc surface has been shown. The effect of corrosive media composition and time-dependent relations of nanoscale film growth on the surface of the metals investigated have been determined. It was assumed that adsorbed MBT anion forms M(MBT) х , a polymeric complex where M = Cu + (x = 1) or Zn 2+ (x = 2).

Abstract:The effect of the adsorption of 5-mercaptopentyl-3-amino-1,2,4-triazole (MPATA) on the corrosive behavior of brass (Cu80/Zn20) in neutral (pH 7.4) borate buffer solutions with and without 0.01 M NaCl was studied. Electrochemical methods show significant decrease of the anodic and cathodic currents on the polarization curves in the presence of MPATA. X-ray photoelectron spectroscopy (XPS) reveals MPATA adsorption on the brass surface from an inhibitor solution. After 17 h of exposure, a mixed complex [Cu x Zn y MPATA z ] with a thickness of about 3-3.5 nm is formed on the surface. This nanolayer has sufficient protective ability to withstand corrosion tests in a salt fog chamber: after 5 days of testing, the samples remain glossy and less than 1% of the surface has been damaged. After corrosion tests in a salt fog chamber, the surface of unprotected samples is enriched with zinc, while at the surface of inhibitor-treated samples, the copper and zinc are present in practically equal contents.

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