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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 the
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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