The electrodeposition of Mn and Zn-Mn alloys from the room-temperature tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide ionic liquid

Zinc, manganese and zinc-manganese alloys were electrodeposited from the hydrophobic room-temperature ionic liquid, tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide. Zn(II) and Mn(II) species needed to produce these alloys were introduced into the ionic liquid by the anodic dissolution of the respective metallic electrodes. The diffusion coefficients of the dissolved Zn(II) and Mn(II) species are not constant, but decrease with the increasing concentrations of these ions, suggesting the formation of aggregated species at higher concentrations. Coatings containing Zn. Mn or Zn-Mn can be obtained by controlled-potential electrolysis. The current efficiencies of Mn electrodeposition in this ionic liquid approach 100%. which is a high improvement comparing to the results obtained in aqueous solution (20-70%). The Mn/Zn ratio of these alloys depended almost completely on Mn(II)/Zn(II) concentration ratio in the ionic liquid. The Zn-Mn alloy deposits obtained in this study were compact, adherent, and exhibited an amorphous structure. The surface morphology of these deposits depended on the Mn/Zn ratio. The addition of Mn up to about 50 a/o improves the corrosion resistance of Zn. However, the addition of Mn beyond this amount decreases the corrosion resistance of the Zn-Mn alloy. (c) 2006 Elsevier Ltd. All rights reserved.