Corrosion and corrosion inhibition by thiourea of bulk nanocrystallized industrial pure iron in dilute HCl solution

The corrosion behaviors of bulk nanocrystallized and coarse grain industrial pure iron (BNIPI & CGIPI) were investigated in 1 mol L−1 HCl at room temperature by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve. Meanwhile, the inhibitive effect of thiourea (TU) on the corrosion behaviors were tested. Results indicate that BNIPI is less prone to occur corrosion than its coarse grain counterpart in blank 1 mol L−1 HCl at room temperature. When CGIPI was immersed for a very short time, namely, 5 min, an inductive loop appears at different concentrations at the Nyquist plots, but it doesn’t appear at those of BNIPI at the same period. A critical concentration of thiourea with the largest Rct in the complex impedance plane appears for both samples.