(174b) Testing Room Temperature Ionic Liquid Solutions

To avoid legacy problems associated with cadmium's carcinogenicity and high toxicity, some new Air Force weapon system steel component designs by original equipment manufacturers (OEMs) specify an aluminum plating instead, to satisfy weapon system corrosion protection requirements.  When these weapon systems come to the Air Logistics Centers (ALCs) for maintenance, repair and overhaul (MRO), repair-scale processes need to be in place to refurbish the coating that is on the exterior and recesses of the components.  The new technologies used by the OEMs to plate these components with aluminum require extensive infrastructure and capital expense.

Technologies that electroplate aluminum from non-aqueous chemistries such as room temperature ionic liquid solutions are being marketed to replace cadmium electroplating for MRO needs, with fewer infrastructure and capital expenses than the OEM's outlays.  In general, room temperature ionic liquids are salts that remain liquid near room temperatures and have a very low vapor pressure unlike organic solvents.  Room temperature ionic liquids can dissolve metal salts from which the metals such as aluminum may be electrodeposited, and have attracted significant laboratory research efforts, because they can be energy efficient and some are considered "green."

The applicability of this technology to DoD plating shops, Air Force ALC plating shops in particular, is of interest.  Despite their promise, there are caveats associated with room temperature ionic liquids, including concerns with the toxicity of a variety of them, and processing difficulties.  In particular, processing must consider the effects of additives on the physical properties of the ionic liquid-based electrolyte.  A review of room temperature ionic liquid additives and their effects on the electrodeposition process will be presented, and screening testing results to date for potential applications will be described.