Electrochemical study of magnesium hydride formation in aqueous solution
Abstract
Magnesium alloys have great potential in automobile and other transportation applications. However, magnesium is a very active metal. Alloying is used to improve mechanical properties and corrosion resistance of magnesium. This paper describes hydride formation in magnesium-aluminium (93.1%Mg-6.9%Al) alloy using electrochemical techniques in aqueous solutions. Corrosion mechanism and hydride formation of studied alloys are analyzed. Hydrogen evolution mechanisms at cathodic potentials are examined. The polarization measurement exhibits two regions with different slopes in the cathodic regime. The linear region of the Tafel lines, beyond -1.6 V (SCE), is likely the potential zone where Mg hydride formation occurs. A.C. impedance measurements are in excellent agreement with the steady-state polarization behavior. An interesting pseudo-inductive loop arises in the complex plots of A.C. impedance in the potential range beyond -1.6 V, and can be attributed to the hydride formation/decomposition process revealed in polarization measurement.