Abstract
The anodic behavior of Ni in 0.01 M H2SO4 without and with the additions of NaCl was studied at a constant current density (2.6 mAcm(-2)). The results depicted that the presence of Cl- ions destroy the oxide layer and induce the pitting corrosion that depends on Cl- ions concentration. The addition of some of the ethoxylated surfactants as inhibitors tolerates the destruction of the oxide layer and inhibits the localized pitting corrosion. Such surfactants shifted the E-pit towards the O-2 evolution potential and enhanced the rate of oxide film repair (partial derivative E/partial derivative t)(i) that depend on the surfactant type and amount. The inhibition efficacy of such compounds is dependent on the adsorption of such inhibitors on the Ni surface via electrons rich centers such as N and O atoms. The inhibition efficacy is based on an adsorption process that obeys Temkin's model by chemisorption mechanism. Some thermodynamic functions accompanied the pitting corrosion and adsorption of inhibitors were computed and explained. The surface morphology for some Ni samples in the aggressive and inhibitive solutions was investigated by SEM.