Effect of Deaeration on the Corrosion of Pure Aluminum and Its Three alloys in NaOH solution at pH=11

Abstract

In this work, the corrosion behaviour of pure Al and its three alloys (Al-Cu-Mg, Al-Mg, and Al-Zn-Mg) was studied in aerated and deaerated 1x10-3 mol.dm-3 NaOHsolutions to show the role of dissolved oxygen gas and its reduction at cathode. Also theaim of this study was to obtain the corrosion parameters such as the corrosion potential(Ecorr), corrosion current density (icorr), cathodic and anodic Tafel slopes (b), andpolarization resistance (Rp) besides the thermodynamic and kinetic functions were alsocalculated (ÄG, ÄS, and ÄH) and (Ea and log A) to comparison these values in thepresence and absence of the oxygen.From the general results for this study can be seen that the polarization resistances forpure Al and its alloys were higher in deaerated solutions and the values of (ÄG) wereless spontaneous in deaerated solution, also the activation energy (energy barrier) washigher in deaerated solution.