Study On Some Brass Coins Of Qing Dynasty Collected In Ezhou Museum

Several brass coins of Qing dynasty collected in the Ezhou Museum,have rusted terribly,and the corrosion is colourful.If observed carefully,we will find that the appearance of some conis is complete,but the interior has been rusted for nearly nothing .We call it"Wormhole-eroded"XRD and XRF were used to identify several brass coins of Qing dynasty collected in the Ezhou Museum, excavated from Ezhou of Hubei province.Based on a careful retrospection into the achievements of past generations and references pulished ,we discuss the component evolution of the brass coins and the corrosive mechanism.At last,I will give some advise to protect the coins. Provide some reference for collecting and protecting coins.The results of simulation experiment are as follows: The reality of the coins contains 34%~41% of Zn,54 %～59% of Cu and 3.51%~7.77% of Pb,the ration of the alloy is steady and scientific,indicating that the technic of the alloy of brass is quite perfect in mid to late Qing dynasty. Zn3Cu2(OH)6(CO3)2 was found in the corrosion for the first time, CuO,ZnO,Fe2O3 and CuCl were found too.The high content of Cl- ,around the local condition (including the polluted environment), may be the main reason that caused those brass coins to be eroded seriously.The complicated electrochemistry made Cu and Zn be dissolved ceaselessly,that may be the reason why the"Wormhole-eroded"formed.