Corrosion Resistance of Aluminum Films Electroplated on Steel from Chloroaluminate Ionic Liquids Containing Toluene as a Co-Solvent

Abstract

Dense and adhesive pure aluminum layers were electroplated on Cu and mild carbon steel plates from the Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride [60 mole percent (m/o) AlCl3] ionic liquid by using current-controlled DC methods. The influence of the current density on the surface morphology and grain size of the electrodeposited Al was investigated by optical microscopy. The corrosion resistance of Al-coated steel was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements for deposits prepared with and without toluene as a co-solvent. Both deposition current density and deposit thickness were crucial factors affecting the structure, integrity, and corrosion resistance of electrodeposited Al layers on steel substrates. Aluminum films prepared in the ionic liquid containing toluene exhibited better overall durability, brightness, and practical corrosion resistance than films prepared from the neat ionic liquid.