Electrochemical Characteristics of <I>Niiro</I>-Colored Cu-1 mass%Au Alloy

The electrochemical characteristics and corrosion behavior of the Niiro-colored Cu-1 mass%Au alloy have been investigated. The oxidation potential of the Niiro-colored Cu-1 mass%Au alloy is higher than that of a raw Cu-1 mass%Au alloy. The reaction electron number of the Cu-1 mass%Au alloy and the Niiro-colored Cu-1 mass%Au alloy is approximately 1 in 5∼14 pH solutions. The electron number of the Niiro-colored Cu-1 mass%Au alloy is similar to that of Niiro-colored Cu. The Niiro-colored Cu-1 mass%Au alloy surface consists of two layers chemically. The thin upper-layer is a copper (II) oxide such as CuO and the underlayer is a copper (I) oxide such as Cu2O. This structure is the same as that of Niiro-colored Cu. The Niiro-colored Cu-1 mass%Au alloy shows good corrosion resistance when the specimens are exposed at 353 K in 90%RH atmosphere. The corrosion current of the raw Cu-1 mass%Au alloy in a solution containing Cl− of 8.3 pH is higher than that of the Niiro-colored Cu-1 mass%Au alloy. These results indicate that the corrosion resistance of the Niiro-colored Cu-1 mass%Au alloy is higher than that of the raw Cu-1 mass%Au alloy without Cl−. A copper oxide layer formed on the surface of the Cu-1 mass%Au alloy protects the alloy from corrosion.