A study of the corrosion inhibition of carbon steel in a bromide solution using fractal analysis

Abstract

This work presents the electrochemical noise results obtained for mild steel corrosion conditions under a lithium bromide–ethylene glycol solution and in the presence of different concentrations of lithium nitrate (LiNO 3) as corrosion inhibitor. Evaluation was performed from the fractal dimension of the electrochemical noise time series obtained using the so called the 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 the different condition signals. This dimension is 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 is the period of time measured and H the Hurst exponent between 0 < H < 1. The calculation of the Hurst exponent and fractal dimension of the time series comes from the slope of the R/ S plot. For comparison electrochemical impedance spectroscopy was also performed. The fractal analysis of electrochemical noise helps to evaluate the inhibitor protection performance under the corrosion conditions tested.