Alloy Plating by Heating Stacked Single Layers and the Possibility of its Application in the Future
The 51st William Blum Lecture
By Hideyuki Kanematsu, Suzuka National College of Technology, Japan
Recipient of the 2012 William Blum NASF Scientific Achievement Award
Editor’s Note: This paper was presented at NASF SUR/FIN 2013 in Rosemont, Ill., on June 10, 2013. A printable PDF version is available by clicking HERE.
In recent years, the plating industry has had the serious challenge of severe environmental regulations. Various "hazardous" metals, e.g., lead, cadmium, etc., have been the target for regulations one by one. As a result, a pessimistic outlook that any metal could be classified into a regulated one by laws has appeared. However, any element, or materials can present both hazardous and benign situations. In many cases, the so called "hazardous" metals would be toxic, when they exist as an ion, but not as a solid metal. Therefore, alloy plating can be one of the best solutions to avoid disuse by the environmental regulations with minor changes for production. Alloy Plating has been conventionally carried out by coelectrodeposition in solutions. On the other hand, the author has proposed a unique method of alloy coating through the combination of heat treatment and multiple plating. In this lecture, the author shows the results and the possibilities for application in the future.
Alloy plating continues to have potential for practical application. Conventionally, it can produce unique properties such as corrosion characteristics, wear resistance, color tone, etc., that cannot otherwise be realized with any single element film. However, recent trends need more innovative developments to solve the practical problems through the utilization of alloy films.
For example, environmental problems seem to hamper the usage of some useful metals (from the functional standpoint at least) at this point. Actually, the use of alloy films can alleviate the environmental burden to some extent. In addition, many emerging needs, such as electromagnetic or optoelectronic properties can appear on the material surface by alloy film formation.
Usually, the alloy film is produced by coelectrodeposition from aqueous solution. However, the author has proposed the combination of surface treatments and heat treatments to produce alloy films in numerous studies.1-25 In this article, I will describe the alloy film formation technique with which my colleagues and I have tried to produce unique materials and describe the characteristics, meaning and the future scope of this technology. Hopefully, this lecture will allow this unique method and technology to produce alloy films and empower many electroplaters and surface finishers to launch new applications of alloy films.
Principles and characteristics of the HSSL process
The proposed alloy film formation process is usually called the Heating Stacked Single Layers Process (HSSL process). As shown in Fig. 1, alloy deposits have been produced to date through coelectrodeposition from aqueous solutions. In this process, the alloying phenomenon occurs during the deposition process. From the standpoint of procedure, the conventional process is composed of a single step.