Bronze mirrors, considered important grave goods, were widely used before glass mirrors in ancient times. Most excavated bronze artifacts are covered with corrosive materials and lose their original colors. More importantly, identifying corrosion characteristics and the manufacturing techniques used for these artifacts are essential for proper artifact preservation. In this study, Early Iron Age bronze mirrors excavated from the Korean Peninsula were examined to determine their microstructures, corrosion characteristics, and production techniques using various analytical methods, such as Micro-Raman spectroscopy and field emission electron probe microanalysis. As a result, sulfides containing iron suggested chalcopyrite use during production or that the sulfides originated from copper, iron, and sulfur residual matte. The analysis also detected corrosion layers with high tin oxide (SnO2) levels and selective corrosion in the α+δ eutectoid phase on the artifact’s surface. In the corrosive layer, cuprite, malachite, and cassiterite corrosion products were detected, and nanocrystalline SnO2 was identified as a characteristic of long-term soil erosion. Identifying these artifacts’ corrosion characteristics and manufacturing techniques is essential and can greatly contribute to proper artifact preservation.

The subject of this study was a bronze sword excavated from the early Iron Age area of Sinpung site in Wanju. SEM-EDS, FE-EPMA and Raman Micro-Spectroscopy analysis methods were applied to investigate the manufacturing techniques and corrosion characteristics. The results of the analysis indicated a casting structure composed of both α and α+δ phases. The α phase developed in the form of dendrite, and it seems that no heat treatment was performed. Through the EDS analysis results, the main components of the bronze sword were identified as Cu, Sn, Pb, etc., and it seems that the cooling rate was different depending on the shape of the dendrite, which is the α phase, and the size and distribution of the Pb particles. Regarding corrosion characteristics, the corrosion progressed considerably to the surface, and a high tin corrosion layer was formed, and lead oxide and copper oxide particles were observed between the corroded microstructures. These materials were identified by Raman spectroscopic analysis as Cuprite (Cu₂O), Malachite (Cu₂CO₃(OH)₂), Cassiterite (SnO₂), Cerussite (PbCO₃), Anglesite (PbSO₄), and Litharge (PbO). Among them, the presence of nanocrystalline SnO₂ confirmed the characteristics of long-term corrosion of bronze artifacts in the burial environment. And, materials such as Cerussite (PbCO₃), Anglesite (PbSO₄), and Litharge (PbO) were found only in weapons and tools such as bronze sword and spear when compared with previous studies.