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### Alternative Plating Processes for Metal Electroplating Based on Ionic Liquids (WP-2316) Objective The objective of this project is to accelerate the application of ionic liquids and other neoteric solvents in nonaqueous electroplating that addresses the Department of Defense (DoD) lifecycle cost and environmental issues related to weapon systems. The team will explore the use of taskspecific ionic liquids and deep eutectic solvents (DES) that mitigate the issues of air/waterstabilities concerning current electroplating baths for electrodeposition of aluminum. New methods of enhancing the conformal coating while mitigating the environmental stability and portable issues will be explored through development of flexible and adaptable plating baths based on ionogel and polymer gel membranes. In addition, the fundamental mechanisms that drive successful electroplating processes in these novel plating processes will be examined. Further, the stability of these nonaqueous plating baths under various operational environments will be investigated to determine the longterm viability of these plating technologies. Finally, the technical issues regarding the use of ionic liquid plating baths—such as ionic liquid regeneration or the cycling, toxicity, and disposal of ionic liquids—will also be explored. Technical Approach To avoid using volatile and toxic organic solvents, chloroaluminatebased ionic liquids have been intensively investigated in electroplating of aluminum. These ionic liquids can be conveniently prepared by combining anhydrous aluminum chloride1methyl3 (AlCl ) with an organic chloride such 3 asethylmethyl imidazolium chloride (EMImCl) and Nbutylpyridinium chloride (NBPCl). Unfortunately, these ionic liquids can be used only in an inertgas atmosphere because of the hygroscopic nature of AlCl and the related chloroaluminate ionic liquids. In this work, the team will use air and waterstable 3 ionic liquids and DES to investigate electroplating of aluminum. The effects of ionic structure, including cation types and anion types, surface activation properties, boundary layer effects of ionic liquids and additives, plating bath process variables, and coating properties, will be systematically investigated. In addition, a new conformal coating using a convenient wrapplating technique based on either an ionogel or a polymer gel membrane will be investigated. Finally, the technical issues regarding the use of ionic liquid plating baths—such as ionic liquid regeneration or the cycling, toxicity, and disposal of ionic liquids—will also be explored.

Benefits The research will benefit DoD by providing a scientific understanding of the key mechanisms and process variables for using ionic liquids in electroplating aluminum. This research will enable the2 / 2 transition of promising ionic liquid processes into DoD’s maintenance and manufacturing systems. It will benefit DoD’s coating manufacturers and electronics assemblers by eliminating or reducing the use of hazardous materials in manufacturing and maintaining DoD systems. (Anticipated Project Completion - 2016)

Points of Contact Principal Investigator Dr. Sheng Dai Oak Ridge National Lab Phone: 865-576-7307 Fax: 865-576-5235 dais @ornl.gov Program Manager Weapons Systems and Platforms SERDP and ESTCP wp @serdp-estcp.org