Electrochemical investigations on pitting corrosion inhibition of mild steel by provitamin B5 in circulating cooling water

Highlights: • Pitting corrosion of steel is effectively reduced by the addition of provitamin B5. • The techniques include potentiodynamic anodic polarization and chronoamperometry. • Physically adsorbed provitamin B5 on the metal surface restricts the corrosion. • Efficiency increased by increasing provitamin B5concentration. • Efficiency decreased by increasing solution temperature and flow rate. - Abstract: The inhibition effect of provitamin B5 on pitting corrosion of mild steel in circulating cooling water containing aggressive anions was investigated by potentiodynamic anodic polarization, chronoamperometric and scan electron microscope (SEM) analysis. The results show that provitamin B5 has a significant inhibiting effect on the pitting corrosion of mild steel. The presence of provitamin B5 shifted the pitting potential (E_pit) to more noble value and decreased the passive current density (j_pass). The efficiency of provitamin B5 increased by increasing its concentration and decreased by increasing solution temperature and flow rate. Chronoamperometry measurements showed that nucleation of pit takes place after the incubation time (t_i). The rate of pit initiation (1/t_i) decrease by increasing provitamin B5 concentration. Activation energies values for the pitting corrosion process in the presence of provitamin B5 were calculated and discussed.