Nano-grain structure of nickel films prepared by emulsion plating using dense carbon dioxide

A nanocrystalline nickel film was prepared by an electroplating method in a constantly agitated ternary system of dense carbon dioxide (CO2) and electroplating solution using a surfactant. The averaged grain size of the plated Ni film was 11.1 nm. In contrast, a nickel film prepared from an electroplating solution by a conventional method without the use of surfactant had an average grain size of about 19.8 nm. The Vickers hardness of the film obtained by the new method was about 680 Hv, while that prepared from the electroplating solution alone was only about 550 Hv. As a consequence, it can be deduced that grain-size strengthening was observed in the electroplated film obtained using this emulsion system.