A new method for electrodeposition of Al coatings from ionic liquids on AZ91D Mg alloy in air

Electrodeposition of Al on Mg alloys from ionic liquids has been achieved scientifically. However, it is difficult to realize industrialized production since the preparation of electroplating bath and electrodeposition process must be carried out under inert atmosphere. A simple and practical method was then proposed to guarantee such manipulations in air by introducing a solid water-adsorbent material as well as a liquid protective film in electroplating bath. In the experimental scale, functional Al layers were successfully electrodeposited on AZ91D Mg alloys from a first-generation ionic liquid AlCl₃/1-butyl-3-methylimidazolium chloride (2 : 1 mol%). The electroplating process was further investigated at constant current and constant potential. A phase of Al of the formed coatings was determined using X-ray diffraction. It was found that a continuous and compact Al film can be obtained on the Mg alloy surface at a constant current along with effective protection, as characterized by scanning electron microscopy, energy disperse spectrometry, potentiodynamic polarization curve and Nyquist plot.