Electrodeposited White Bronzes: A Comparison between Zn-Bearing and Zn-Free Coatings ^†

Abstract

White bronzes are ternary alloys composed of Cu, Zn and Sn, named after their bright whitish color. This class of alloys shares excellent hardness, corrosion and tarnishing resistance, and is commonly adopted in galvanic industrial processes as technological grade coatings to obtain layers with particular aesthetical and/or anticorrosive properties. Despite the widespread employment of white bronzes in fashion and the electronics industry, the recent literature lacks a characterization of these electrodeposited alloys with respect to more common binary (Cu-Sn) white bronzes. In this presentation, a thorough characterization of a commercial ternary Cu-Zn-Sn white bronze, produced by electrodeposition, is reported. Structural, chemical and physical characteristics of the deposited coating were investigated by various techniques (e.g., FIB/SEM, XPS, XRD, EDX, micro-hardness, color and corrosion tests). Results were compared with a similar set of measures obtained from a binary electrodeposited Cu-Sn white bronze (with a high tin content), in order to shed some light on the influence of Zn in the coating properties.