Hard Pure-Gold and Gold-CNT Composite Plating Using Electrodeposition Technique with Environmentally Friendly Sulfite Bath

Abstract

Gold was used by Chinese and Egyptians of ancient times (at least ca 3000 BC). For many years, gold based materials have received great attention from people, due to the good conductor, high chemical stability, unique optical and processable properties. Electrodeposition technology is a long established technique for synthesizing metals on conductive substrates. Advances in equipment and creations of nanomaterials could carry out new technological progress, a large duty ratio with a pulse overvoltage became possible and new composite fillers (for example, carbon nanotubes: CNTs) appeared. Moreover, environmental considerations have become more important as Sustainable Development Goals (SDGs). SDGs were adopted at the United Nations Summit in September 2015 and are the goals set by the 193 member countries to achieve in the 15 years from 2016 to 2030. For the global environment and workers, friendly manufacturing methods have become more important. In this chapter, two nanostructured golds (hard pure-gold plating and gold-CNT composite plating) are discussed. They are a method of hardening the metal as pure-gold by pulsed electrodeposition and a method of combining CNT by controlling the zeta potential with additives, and their application as a contact material was investigated. Additionally, the synthesis and characteristics of electrostatic deposition films with properties using environmentally friendly sulfite bath are discussed.