The metal-manufacturing method and smelting temperature of ancient metal-production processes have been studied by analyzing the principal elements and microstructures of slag. However, the microstructure of slag varies according to the solidification cooling rate and types and relative amounts of various oxides contained within the smelting materials. Hence, there is a need for accurate analysis methods that allow slag to be distinguished by more than its composition or microstructure. In this study, the microstructures of slag discharged as a result of smelting iron sands collected from Pohang and Gyeongju, as well as the slag excavated from the Ungyo site in Wanju, were analyzed by using metalloscopy, scanning election microscopy-energy dispersine X-ray spectroscopy(SEM-EDS) and wavelength dispersive X-ray fluorenscence(WD-XRF). Furthermore, the microcrystals were accurately characterized by performing Raman micro-spectroscopy, which is a technique that can be used to identify the microcrystals of slags. SEM-EDS analysis of Pohang slag indicated that its white polygonal crystals could be Magnetite; however, Raman micro-spectroscopy revealed that these crystals were actually ulvöspinel. Raman micro-spectroscopy and SEM-EDS were also used to verify that the coarse white dendritic structures observed in the Gyeongju-slag were Wüstites. Additionally, the Wanju slag was observed to have a glassy matrix, which was confirmed by Raman micro-spectroscopy to be Augite. Thus, we have demonstrated that Raman micro-spectroscopy can accurately identify slag microcrystals, which are otherwise difficult to distinguish as solely based on their chemical composition and crystal morphology. Therefore, we conclude that it has excellent potential as a slag analysis technique.

This study attempted to review the chemical composition of 25 samples of Sangpyeongtongbo having different manufacturing place and period, and then to find the manufacturing method. As a result of chemical composition analysis of Sangpyeongtongbo, main components include Cu, Zn and Pb, and some samples contained Sn and Fe. But, the chemical composition of each Sangpyeongtongbo varied with big differences. When the main content change was examined, Cu and Sn became decreased at the later period, and Zn and Pb had higher contents. The difference in the ingredient content had close relation for the profit of Sangpyeongtongbo. When refined microstructure was observed, 25 kinds of Sangpyeongtongbo had developed different types of microstructure such as dendrite, large grain and grain refinement. But, 25 kinds of Sangpyeongtongbo had no heat treatment processing. And, the types of microstructure were difference, which seems because different microstructure was developed due to the difference of Sn and Fe and cooling speed in Sangpyeongtongbo.