Abstract:It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl₃ room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl₃ ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation (400 mL/L HF acid, 10 min), zinc-immersion (20 min) and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl₃ using direct current plating.

Key words: magnesium alloys; electroplating; pretreatment procedure; aluminum; ionic liquids