日本金属学会誌

J. Japan Inst. Metals, Vol. 74, No. 9 (2010),
pp. 598-604

Microstructural Observation of Base Metal and Corroded Layer of a Copper Bowl Excavated from Mukaiyama Ruins, Nara

Takekazu Nagae1 and Atsushi Hadano2

1Faculty of Art and Design, University of Toyama, Takaoka 933-8588
2Archaeological Institute of Kashihara, Nara Prefecture, Kashihara 634-0065

Abstract:

The microstructure of a copper bowl excavated from an Edo-period grave in Mukaiyama Ruins in Nara prefecture has been investigated. The sample was subjected to optical microscopy, scanning electron microscopy, electron probe microanalysis and X-ray diffraction analysis to obtain information about the microstructure of both the base metal and the corroded layers. The bowl was made of copper containing 0.9% lead. Annealing twins were observed in the α-Cu phase, which establishes that the bowl was forged and annealed. The corroded layers were composed mainly of cuprite, malachite and copper phosphate. It is thought that the copper phosphate acted as an inhibitor to corrosion.


(Received 2010/4/21)

Keywords:

copper, microstructure, twin, corrosion in soil, excavation, cuprite, malachite, phosphate, inhibitor


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