Comprehensive Research on the Layered Corrosion of Archaeological Copper Wares: A Case Study from Qinghai, China

Abstract

ABSTRACT In this study, copper wares excavated from tombs in the Qinghai Province of China were investigated. Using varied analysis methods, this study analyzes the layered corrosion products of copper ware. Furthermore, it discusses the relevant corrosion mechanism along with the burial environment, condition, and manufacturing craft. The forged copper wares appear to be in a state of stratified corrosion in the burial environment. Beginning from the outside and moving toward the inside, the following layers were observed: malachite and azurite; atacamite and clinoatacamite; cuprite and clinoatacamite; and the innermost layer, which is a residual metal layer in some regions. In the cuprite layer, the presence of clinoatacamite was observed to destroy the structure of the cuprite and form fine stratification, which, in turn, promoted the further development of chlorine-containing corrosion products and led to the ‘peeling off’ of copper ware. This study explores the destructive corrosion caused by Cl in copper ware.