Then, a 12 nm cobalt-rich layer and a 4 nm pure gold layer were electrodeposited on the polycarbonate film with the designed bath to obtain Au/Co multi-layer nanowires.Īu–Co alloys and Au/Co multi-layers have been fabricated from sulphur-containing cyanide-free electrolyte 17,18 Results showed that a low citric acid concentration (0.47 M) at pH 6.15 is favourable for multi-layered Au/Co deposits with disparate compositions in each layer. Au-0.1 wt% Co alloy and Au-97 wt% Co alloy multi-layers were obtained. Ag/AgCl) potential, whereas gold-rich deposits were deposited at −0.049 mV ( vs. In electrodeposition, cobalt-rich deposits were deposited at −1.1 mV ( vs. 13–16 fabricated Au/Co multi-layer films by electrodeposition in cyanide-containing electrolyte. 10 An Au/Co granular structure with GMR of 2.4% at 10 K, fabricated by a melt-spinning technique was reported. measured a GMR of 3% at 4.2 K for Co/Au sandwiches, fabricated by ultrahigh vacuum evaporation. 10,11 German physicist Peter Grünberg and French physicist Albert Fert observed giant magnetoresistance, 12 in iron/chromium/iron and iron/chromium multi-layer films in 1988. 6–9 Development of new structure and functional coatings has become a new focus of Au–Co alloy research. 3–5 It makes the structure and function of the coating develop to diversification. 1,2 The performance of gold cobalt alloy coating is adjustable with the increase in cobalt content, which breaks the traditional idea of uniform coating based on gold. The traditional application of Au–Co alloy is based on the physical and chemical properties of gold. Introduction Au–Co alloy (so called hard gold) electroplating is widely used in printed circuit board (PCB) manufacturing, due to its good contact resistance performance, high hardness and chemical stability. Using an optimised cyanide-free electrolyte produced Au/94.07 at% Co–Au multi-layers with a gold layer of approximately 20 nm and a 94.07 at% Co–Au alloy layer of approximately 90 nm in the 5,5-dimethylhydantoin-containing, cyanide-free system. saturated calomel electrode (SCE)), only gold was deposited when the potential was negative (−0.8 V vs. When the electrode potential was positive (−0.6 V, −0.7 V vs. The co-deposition of gold and cobalt in this study system was canonical. A large current density and high over-potential value resulted in high cobalt concentration. Results showed that low current density and over-potential value promoted Au deposition. The effect of current density and potential values on the deposited composition was investigated. Firstly, an optimised electrolyte for Au–Co alloy electrodeposition was obtained from orthogonal experiments. A novel cyanide-free electrolyte was used in electrodepositing Au/Co–Au nano-multilayers.
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