Corrosion Behavior in Highly Concentrated Sodium Chloride Solutions of Nanocrystalline Aluminum Processed by High Energy Ball Mill
Sherif, El-Sayed M. . 2016
The manufacturing of nanocrystalline aluminum using mechanical alloying technique after different ball milling times, namely 1, 3, and 5 h was reported. The effect of milling period on the corrosion behavior of the manufactured aluminum in 4.0 wt.% sodium chloride (NaCl) solutions was carried out. The corrosion measurements were studied using potentiodynamic polarization (PP), chronoamperometric current-time at constant potential value (CCT), and electrochemical impedance spectroscopy (EIS) techniques. It has been found that the increase of milling time from 1 h to 5 h refines the grain size of the aluminum as was confirmed by the X-ray diffraction investigations. The corrosion tests indicated that the increase of milling time increases the reactivity of the aluminum surface and thus increases its corrosion. This was confirmed by the data obtained from polarization measurements, where the corrosion current density, the corrosion rate, the anodic current and cathodic current were increased with increasing the milling time. This effect was also noticed to increase the values of the absolute currents for aluminum with time when applying an anodic potential value. EIS measurements also confirmed the data obtained by PP and CCT that refining the grain size of the aluminum increases the corrosion of aluminum in the sodium chloride solutions.
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