An Industrially Convenient Method of Synthesizing Pore-free Aluminum Coating Employing Unpurified First-Generation Ionic Liquid Electrolyte

Aluminum electrodeposition using first-generation ionic liquid is gaining popularity primarily because of its anti-corrosion performance. Prior to the aluminum electrodeposition, either the chemicals used for the electrolyte preparation are typically dried in the vacuum oven, or the prepared electrolyte is purified by dipping a piece of pure aluminum for several days, to remove impurities, including moisture. Unnecessary time consumption, additional expenditure, and complexities in handling the chemicals, arising from drying and purifying, greatly impede the scalability of aluminum electrodeposition in wider industrial applications. If an unpurified electrolyte is used, gas evolution arising from the side reactions occurs during electrodeposition, resulting in the development of pores in the coating. With pulse electrodeposition, it is demonstrated that a compact, uniform, and pore-free coating can be developed even with the unpurified electrolyte. Scanning electron microscopy and 3D optical profilometry employed for evaluating morphology and topography revealed the development of a homogenous, smooth, and pore-free aluminum coating with the pulse electrodeposition from the unpurified electrolyte. The micro-indentation test showed that the hardness of the coating can be improved with the pulse technique. Potentiodynamic polarization and electrochemical impedance spectroscopy demonstrated the development of a more anti-corrosive coating using pulse electrodeposition.