Color characteristics and anti-tarnish property of gold film of Cu-Zn alloy

The Color characteristics at high-temperature and tarnishing behavior in artificial sweat solution of gold-imitation Cu-Zn alloy were studied according to charoma theory and microstructure analysis on the basis of scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The structures and anti-tarnishing mechanism of golden film were also investigated. The results show that a 24 K-gold-like copper alloy with excellent color-stable property can be obtained through thermally gold-imitation treatment and anti-tarnish treatment. With the increase of Zn content, ZnO is formed rapidly while sepia CuO is suppressed on the outermost oxidation film at high temperature. The protective film made up of Cu-BTA molecules and Cu-AMT molecules on loose surface of ZnO gradually become compact, which can fill the defects caused by the drop of α-phase and β-phase in artificial sweat solution at 50 ℃. Additionally, water molecules, corrosive Cl-and NH+ in material clearance are displaced, avoiding the formation of chloride and amides with other colors.