Comparative study of protective magnesium deposit behaviour obtained by continuous and pulsed currents from methylmagnesium chloride solution

Pulsed and continuous (or direct) currents were used for the electrodeposition of magnesium from methylmagnesium chloride solution. The analytical characterization of the magnesium coating was performed by scanning electron spectroscopy (SEM) and the X-ray diffraction (XRD). The electrochemical behaviour of the steel substrate coated by magnesium was assessed by electrochemical impedance spectroscopy and potentiodynamic polarization curves. The deposits morphology was quite different; it changed from smooth and irregular with cracks for the deposit obtained by continuous current (cc), to granulate with an average grain diameter of about 3 µm for the deposit obtained by pulsed current (pc). The electrochemical results showed that the protection of the steel substrate against corrosion was better with the magnesium deposit obtained by pulsed electrodeposition process.