Formation mechanism of copper-gilded coronet ornaments excavated from a Sui or early Tang tomb situated in Xi’an, Shaanxi

Abstract The formation of the gold layer in mercury gilding occurs through heating a amalgam. As result, mechanism and technical characteristics gilded products are closely related to temperature at which they heated. In this study, XRD XPS analysis copper-gilded coronet from Sui or Tang dynasties revealed that Au 3 Cu was one main phases layer. Therefore, base on thermodynamic stability ordered like Cu, estimated for ranged 240 285 ℃. Furthermore, SEM–EDS cross-sectional concentration distribution indicated diffusion distance during did not exceed 2 μm. At 240–285 ℃, diffused along defects layer, process followed Fick’s second law. Previous research has defect path coefficient is order 10 –12 cm /s, time typically considered be 15 min. Using equation, calculated aligned with behavior confirming inferred range. Additionally, these temperatures, formed solid-state reaction amalgam bonded substrate Cu.