Corrosion behavior and inhibitive effects of organotin compounds on nickel in formic acid

Abstract

Corrosion behavior of nickel (Ni) in different compositions of formic acid (HCOOH) at 30°C was studied using the potentiostatic polarization method. The shape of the polarization curve was evaluated, and the corrosion current density, critical current density, and passive current density were determined. HCOOH solutions of different composition were aggressive for the anodic dissolution of Ni, except for 20 and 30 mol/O HCOOH, in which feeble passivity was observed. The organometallic compounds dibutyltin dichloride, phenyltin trichloride, diphenyltin dichloride, and triphenyltin chloride ([C6H5]3SnCl), reduced the corrosion rate of Ni in 20 mol/O and 40 mol/O HCOOH. (C6H5)3SnCl was the most efficient. Inhibitive action was explained on the basis of adsorption following the Langmuir adsorption isotherm, with the highest surface coverage given by (C6H5)3SnCl. The inhibitive action of organometallic compounds toward Ni in HCOOH was caused by the group and delocalized Π electrons.