Analysis of Michelson Optical Interferometry Using Recurrence Plots During Corrosion of Aluminium in NaCl Solution

Abstract

This work presents the assessment of the dynamics of electrochemical corrosion of pure aluminium through Michelsońs optical interferometry measurements. These data were analysed using a new analysis method named Recurrence Plots (RP) analysis. This method allows the assessment of the dynamics of the pitting corrosion process of aluminium in chloride solution at room temperature. After electrochemical potentiodynamic polarization curve characterizing the system corrosion regions was obtained, interferograms for these different regions (potentials) under potentiostatic control were obtained, and digitally transformed. The analysis of these optical variable-time series was conducted using a recurrence plot (RP) and quantification analysis (RQA). From the analysis it was possible to determine the percent recurrence (%R), the percent determinism (%D) and the information Entropy of the aluminium corrosion process for different electrochemical potentials. These parameters increased with the polarization potential defining the different corrosion conditions of the metal sample from the active, passive pre-pitting and pitting regions within the polarization curve. From the interferometric measurements and RP analysis, it was possible to identify the different corrosion conditions and establish that pitting corrosion induced a more deterministic dynamics on the electrochemical process.