Research on the corrosion mechanism of bronzes unearthed from Han tombs in Guangzhou
Many bronzes have been unearthed from Han tombs in Guangzhou,but their corrosion and mineralization are very serious.In order to study the mechanisms of corrosion,metallographic analysis,SEM-EDS,XRD of corrosion products,soil pH measurement and soluble salt determination were used.Typical samples extracted from bronze ware were analyzed with regard to three aspects:matrix,corrosion products and soil.The results show that there are two kinds of materials in eight of samples,namely seven pieces of lead-tin bronze and one piece of tin bronze.The mechanical properties of the alloy were not the best because of the fluctuation of the ratio of lead to tin.According to the microstructure of the matrix,most of the samples were cast microstructure.The dark field demonstrated that the mineralization corrosion process was from inside to outside.The XRD results show that all lacked copper chloride.The content of chloride ion in the burial environment of Guangzhou is not low compared with other areas in China,but the acidity is the strongest.The lead and tin in the ternary alloy were anodes relative to copper.There were a lot of intercrystalline and grain boundaries in dendrites and the potentials of different phases were different.There were a lot of inclusions and much shrinkage,the chemical composition was not uniform,the impurity potential of the alloy was higher than that of the matrix,and a lot of microcathodes and microanodes were formed.However,the main corrosion process of bronze vessels unearthed from Han tombs in Guangzhou area was H+corrosion.The acidic soil environment,due to the abundant groundwater in Guangzhou,as well as abundant oxygen and carbon dioxide make copper and lead ions move outwards continuously,which results in serious corrosion and mineralization of bronzes.
Han tombs in GuangzhouBronzesTesting and analysisCorrosion mechanism
国家科技期刊平台
NSTL
万方数据
