Study On The Corrosion Products Of Bronzes Unearthed From Changning Dadianshan Cemetery In Baoshan City

Dadianshan Cemetery in Changning is the most important discovery of the archaeology of Ailao bronze ware in recent years,of the age between the late Spring and Autumn Periods and the Eastern Han Dynasty.Its special earth cave burial form and many singular bronzes were first discovered in Yunnan.In 2019,it was rated among the 8^th group of key cultural relic sites under state protection.However,the bronzes unearthed were seriously corroded and mineralized,making it urgent for us to study the preservation thereof.In this paper,using super depth-of-field microscope,Raman spectroscopy,SEM-EDS,X-ray diffractometer,etc.,samples of corrosion products of bronzes in the cemetery and the covering soil were analyzed to reveal the structure and components of the corrosion,and soil acidity and alkalinity,phase and anions and cations.On such a basis,characteristics of the corrosion products and their relationship with the burial environment were discussed,and similarities and differences between earth cave tombs and pit tombs in bronze corrosion products compared and analyzed.Main corrosion products were Tin oxide,malachite and azurite.Combined with analysis of soil samples,it was concluded that the serious corrosion of bronzes was closely related to the high viscosity,high water content,soil acidity and other physical and chemical properties of the buried soil.Higher carbonates corresponded to more basic copper carbonate and lead carbonate.Bronzes unearthed from earth cave tombs showed richer and more complex types and structure of corrosion products,the environmental factors of which lay in the complex burial environment,higher water content and lower porosity for kaolinite-dominated clay minerals in soil,facilitating the generation of azurite.Analysis of corrosion products of unearthed bronzes from Dadianshan Cemetery helped us further understand bronzes unearthed therefrom,and provided some basic data for studies on preservation of seriously mineralized bronze ware.According to the corrosion characteristics and degree of mineralization,advice on preservation of unearthed bronze ware was given,providing reference and guidance for future preservation of cultural relics.