Fabrication of Au micro-particles using physical methods

Abstract

In recent years, the demand for fine Au particles in advanced science and technology has increased. Chemical and physical methods are typically employed to produce fine metal particles. To prepare Au particles, chemical methods are primarily adopted because Au is malleable. The direct physical energy from the crusher transforms Au into a thin film instead of fine particles. In this study, we investigate a thin-film rupture method that uses indirect energy provided by cavitation to create Au particles. We hypothesized that the microbubbles generated in the solution owing to cavitation would apply shock waves to the surface of the Au thin film, break the film, and facilitate the formation of fine particles. The Au thin film to be fractured was fabricated via electrolytic plating on a Zn–Al alloy plate. Au plating on a Zn–Al alloy plate can be peeled off after a thin Au-plating film is formed. A thin Au-plating film with a three-dimensional structure was fabricated by adjusting the plating bath temperature and agitation speed of the plating solution during plating. We successfully obtained Au particles by applying shock waves from microbubbles to a thin Au-plating film. Furthermore, the surfaces of the fine Au particles were protected by adding a dispersant. As a result, collisions between Au particles were suppressed, and Au particle sizes of approximately 5‒10 μm were obtained.