The Study On The Electrochemical Behavior Of Magnesium And Aluminum Alloyes

The magnesium alloy and aluminum alloy are used to be negative electrode in cell, which is greatly concerned because of their higher energy density and lower price. However, they haven't been widely used partly due to such problem as passivation and corrosion, which makes them difficult to satisfy the practice. Therefore, it would be important significance and practical value to study the mechanism of magnesium and aluminum electrode and the effect of various additives on electrochemical performance.In this dissertation, the electrochemical performance of AZ31 and AZ61 alloys in 2 mol/L Mg(ClO4)2 solution were firstly investigated by means of weight loss, linear sweep voltammetry, open circuit potential-time, chronopotentiometry. The effect of hexadecyltrimehtylammonium bromide (CTAB) on the electrochemical performance of magnesium alloy is also studied. Results indicate that the electrochemical performance of two kinds of magnesium alloy is very good in 2 mol/L Mg(ClO4)2 solution. On the basis of LSV, the electrochemical performance of AZ31 in Mg(ClO4)2 solution is better than AZ61's, by contraries, the results of CP indicate that AZ61 is more excellent than AZ31 including discharge current efficiency, electrode potential, potential lag, etc.The effect of inhibitor (CTAB) on electrochemical performance of AZ31 and AZ61 is good. The best concentration in 2 mol/L Mg(ClO4)2 solution is AZ31=12mmol/L and AZ61=10mmol/L.Furthermore, the electrochemical performance of aluminum alloy in sodium solution at different temperature was studied. Result indicates that open circuit potential changes from positive to negative and corrosion becomes serious with the temperature increasing. After the NaAlO2 is added, the open circuit potential and discharge potential changes to more negative, and corrosion becomes more serious. It is proved the effect of NaAlO2 on the electrochemical performance of aluminum is disadvantageous. It has been shown that passivation of aluminum decrease and that the potential moves to more negative when the NaF is added into 4mol/L NaOH. The concentration of NaF is from 30mmol/L to 60mmol/L with the temperature increasing. When Na2SnO3 is added, result shows that the potential moves to more negative, that lag-time of potential is shortened and that passivation decrease. The best concentration of Na2SnO3 is 3 mmol/L.