Analysis of electrochemical current noise data arising from corrosion of Al alloy in a gel electrolyte by wavelet and recurrence methods

Abstract

Gel electrolytes are preferred to liquid electrolytes due to the slower movement of ions, thereby lower damage. However, the use of gel electrolytes causes an increase in corrosion susceptibility due to the non-flat surfaces of cells. The use of corrosion inhibitors is one of the most practical methods for corrosion protection. The effect of penicillin as an inhibitor in a gel electrolyte containing 3.5% NaCl was investigated on the corrosion of 6061 Al alloy. Both electrochemical impedance spectroscopy (EIS) and electrochemical current noise (ECN) techniques were employed for data collection. The ECN data were analyzed by both the wavelet transform and the recurrence methods. According to EIS data, the inhibition efficiency (IE) increased from 77% to 94% for up to 15 days. The IE values obtained from ECN data increased from 81% to 90% over immersion time. The recurrence plots of the blank sample proved the increase of pit density with increasing the immersion time from 1 day to 15 days. However, the SDPS plots of the blank sample showed an increase of pit size with increasing the immersion time from 1 to 15 days. The recurrence plots proved the inhibition effect of penicillin on the corrosion of Al alloy that is apparent from the significant lowering of vertical black lines.