Electrochemical Behavior of Aluminum in Sodium Chloride Solutions in the Presence of Zirconium(iv), Magnesium(ii) and Lanthanum(iii) Ions

The electrochemical behavior of A5 grade aluminum (99.5%) in 0.5 M NaCl solutions with the addition of magnesium, zirconium and lanthanum nitrates was investigated by the potentiodynamic method (solution 1 - 0,045 МZr4+ + 0,5 МNaCl; solution 2 - 0,007 М La3+ + 0,045 Zr4+ + 0,5 МNaCl; solution 3 - 0,007 М La3+ + 0,045 Zr4+ + 0,047 Mg2+ + 0,5 МNaCl) at scanning speeds of 1, 2, 5, 10 mV/s. The influence of lanthanum nitrate and magnesium nitrate additives on the electrochemical characteristics of an aluminum electrode is considered. It was revealed that at all scanning speeds, the obtained data have approximately equal values in the studied solutions and the appearance of the polarization curves is similar to that for a solution of 0.5-1 M sodium chloride. It was also revealed that the introduction of lanthanum nitrate and magnesium nitrate into a sodium chloride solution leads to a shift in the corrosion potential to the region of more positive values by 30-90 mV, as well as breakdown and passivation potentials. When considering cyclic voltage curves, it was revealed that when magnesium nitrate (solution 3) is introduced into the electrolyte, current fluctuations are not observed in a wide range of potentials, which occurs in solution 2. This effect can be explained by the inhibitory effect of nitrate ions, the content of which increased in solution when magnesium nitrate was added. When considering the cathode polarization curves, it was revealed that there are no significant changes in the electrochemical behavior of aluminum when Mg2+ salt is added to the solution. It follows from this that the electrochemical behavior of the aluminum electrode is more influenced by the anionic composition.