Study of pitting corrosion on mild steel during wet-dry cycles by electrochemical noise analysis based on chaos theory

Electrochemical noise (EN) was used to investigate the corrosion behaviour of mild steel (Q235) in 0.1 M Na2SO4 and 0.1 M NaCl aqueous solutions during wet-dry cycles. The positive fraction and value of the Largest Lyapunov Exponent (LLE) of electrochemical current noise (ECN) were found out to represent the number and isolation degree of the pits formed in two electrolyte conditions. The calculated results indicate that metastable pits are more plentiful and uniformly distributed in wet cycles and in Na2SO4 solution than those in dry cycles and in NaCl solution respectively. (C) 2012 Elsevier Ltd. All rights reserved.