Aluminum deposition devices and their use in spot electroplating of aluminum

Abstract

A method for spot electroplating aluminum onto a metallic substrate without submersion or dipping of the metallic substrate in an electroplating bath, the method comprising: (i) spot coating said metallic substrate with an aluminum ion-containing electrolyte contained within a protective structure possessing at least one aperture, and releasing said electrolyte from said at least one aperture onto said metallic substrate to form a coating of said electrolyte thereon, wherein said electrolyte is in contact with an anode; and (ii) applying a voltage potential between the anode and metallic substrate polarized as cathode when the aluminum ion-containing electrolyte is released from said aperture and forms a coating on the metallic substrate, to produce a coating of aluminum on the substrate. Devices, such as brush and ball pen plating devices, for achieving the above-described method are also described.

Description

[0001]This invention was made with government support under Prime Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of Energy. The government has certain rights in the invention.FIELD OF THE INVENTION[0002]The present invention relates generally to methods and aluminum-containing electrolytes useful in the electroplating of aluminum, and more particularly, to devices useful in spot plating aluminum onto various metallic substrates.BACKGROUND OF THE INVENTION[0003]Metal surface coating has played an important role in extending the life cycle of structural materials commonly used in large rugged equipment for use on land, air, and sea. Aluminum and its many versatile alloys are routinely used as surface coatings for the corrosion protection of many metals, offering both barrier and sacrificial protection. In addition, aluminum and its alloys are being considered as favorable alternatives for cadmium coatings on the protective shells of electrical connectors in military gro...

AI Technical Summary

Benefits of technology

The present invention provides a solution for the problem of having to implement costly precautions against moisture during aluminum electroplating in the art. This is achieved by employing applicator devices that include a protective structure within which an aluminum ion-containing electrolyte is incorporated, with the provision of apertures in the protective structure to permit release of the electrolyte onto a metallic substrate. The applicator device can be, for example, a polymer membrane, a brush plating device, or a ball pen plating device. The electroplating method involves making the electrolyte in contact with an anode and applying a voltage potential to produce a coating of aluminum within an area bounded by the coating of the electrolyte. A further advantage of the methods described herein is the ability to spot electroplate metallic substrates that are generally too large or cumbersome to electroplate by immersing or dipping into a bath.

Problems solved by technology

Unfortunately, neither aluminum nor its alloys can be electrodeposited from aqueous solutions because hydrogen is evolved before aluminum can be plated.

Not surprisingly, the technique raises a number of environmental and safety objections because the alkyl aluminum compounds are pyrophoric and toxic, and the toluene solvent is flammable and can lead to volatile organic compound (VOC) emissions.

The inefficiency of aqueous electroplating also makes it a major energy consumer.

Therefore, they are amenable for the electroplating of reactive elements, which is impossible using aqueous or other organic solvents.

However, because of the hygroscopic nature of AlCl3 and the resulting chloroaluminate, the electroplating generally must be performed in an inert gas atmosphere, which significantly increases cost and complexity of the process.

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