The Effect of Inorganic Inhibitors on Corrosion of Aluminum Alloy with Electrochemical Noise and Electrochemical Impedance Spectroscopy

Electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS) measurements were employed to study the corrosion behavior of Aluminum alloy in Na2SO4 (0.5M)/NaCl ( 0.2M) solution in presence of inorganic inhibitors. The time series noise patterns were transformed into frequency domain by fast Fourier transformation (FFT) and their power spectrum densities ( PSDs) at specified frequencies were determined and compared with the EISand polarization results . EN,EIS and polarization confirm each other . The inhibitive effect of these anions increases in the order :CrO4 2->Cr2O7 2->NO3->WO4 2->MoO4 2-> NO2-.The results showed that the slopes of PSDs current (roll off) were less where inhibition effeciency was more . The spectral noise impedace and the modulus of the impedace recorded using impedace spectroscopy showed good agreement.

Keywords:

Aluminum Alloy , Pitting Corrosion , Inorganic inhibitors , Electrochemica Noise , Electrochemical Impedace Spectroscopy.