Fractal Analysis of the Corrosion Inhibition of Carbon Steel in a Bromide Solution by Molybdates

Electrochemical noise results were obtained for mild steel corrosion in a lithium bromide-ethylene glycol solution with different concentrations of lithium molybdate (LiMoO3) as corrosion inhibitor. The evaluation was performed from the fractal dimension of the electrochemical noise-time series obtained using the so called Rescale Range Analysis (R/S) proposed by Hurst. The steel under different inhibitor concentrations were exposed to a lithium bromide environment and electrochemical potential/current noise measurements were performed. Afterwards, the fractal dimensions were calculated from the time series obtained for different condition. This dimension was obtained from the empirical law R/S = (τ/2)H where R represents the difference between the maximum and minimum values of the variable, S the standard deviation of the time series, τ the period of time measured and H the Hurst exponent (0 < H < 1). The calculation of Hurst exponent and fractal dimension of the time series comes from the slope of R/S plot. Electrochemical impedance spectroscopy was also performed for comparison. The fractal analysis of electrochemical noise helps to evaluate the inhibitor protection performance under the tested corrosion conditions.