Analysis of the Corroded Layers of Ancient Bronze Mirrors Found in Clay
Analysis of the Corroded Layers of Ancient Bronze Mirrors Found in Clay
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粘土中发现的古代铜镜的腐蚀层分析
DOI：
10.2320/jinstmet1952.66.10_1030
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发表时间：
2002
影响因子：
--
通讯作者：
Yasuji Shimizu
中科院分区：
文献类型：
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作者：
M. Yokota;Fuminori Sugaya;H. Mifune;Y. Kobori;K. Shimizu;Kazuo Nakai;Shin;Yasuji Shimizu
出土的青铜器，取决于它们在地下的时间和条件，通常是外部腐蚀，内部有复杂的腐蚀层。到目前为止，我们小组已经对18面古代铜镜进行了冶金研究，并证实在铜镜的腐蚀层内和表面形成了纯铜块和几种未知的腐蚀产物。据此，采用EPMA、SEM、m、XRD、XPS等分析手段对腐蚀产物进行了分析，探讨了腐蚀产生的可能原因。研究结果如下：(1)最外层腐蚀层i形成无定形SiO2；(2)第二层和第三层形成Cu2O （cuite）和Cu (OH)2;(3)第四层形成CuSnPb络合物氧化物。还检测到少量的PbSO4和Sn有机化合物。(4)我们观察到，经过机械抛光并静置约一个月后，腐蚀层的抛光表面，特别是第IV层，Cu2S（辉铜矿）形成了类似霉菌的形态。推测Cu2S是硫酸盐还原菌的产物。许多纯铜块以层或颗粒的形式出现，并倾向于在第四层附近形成。这些分析的证据表明，微生物可能是在从粘土中挖掘出来的古代铜镜中发现的腐蚀的原因。
Excavated bronze objects are, depending on how long they were in the ground and under what conditions, generally corroded externally as well as having intricately corroded layers inside. To date, our group has performed metallurgical investigations on 18 ancient bronze mirrors and confirmed that pure copper lumps and several varieties of unidentified corrosion products are formed in and on the corroded layers of the mirrors. Accordingly, we investigated the corrosion products by using EPMA, SEM, mXRD and XPS, and discussed the possible causes of corrosion. The results are as follows; (1) Amorphous SiO2 had formed in the outermost corroded layer I. (2) Cu2O (cuprite) and Cu (OH)2 had formed in the layers II and III, which comprise the first two internal layers adjacent to layer I. (3) CuSnPbcomplex oxide had formed in layer IV, the next internal layer. Small amounts of PbSO4 and an Snorganic compound were also detected. (4) We observed that Cu2S (chalcocite) forms like mold on the polished surface of the corroded layers, especially notable on layer IV, after being mechanically polished and left to stand for about one month. Cu2S is presumed to be the resultant of sulfate reducing bacteria. (5) Numerous pure copper lumps appeared in layers or particles and tended to form in the vicinity of layer IV. (6) The evidence from these analyses suggest that microorganisms could have been the cause of the corrosion found in ancient bronze mirrors excavated from clay.