전자저널 > 전자저널 > Color enhancement of freshwater pearl by heat treatment

Color enhancement of freshwater pearl by heat treatment

Soo-Jung Son, Jin-Gyo Seo, Jong-Wan Park

Department of Materials and Chemical Engineering, Graduate School of Engineering, Hanyang University, Seoul 133-791, Korea

In this study, we conducted heat-treatment on freshwater cultured pearls at various conditions in other to improve their color. Also, after heat treatment, we used the UV-Vis, ED-XRF and SEM to investigate changes freshwater cultured pearls’ color, composition and internal structure. UV-Vis analysis showed the reflectivity of samples increased at most heat-treatment conditions although the reflectivity decreased at a certain temperature and duration. At 100°c/8 h, 120°c/6 h and 140°c/4 h, the reflectivity increased highest. In proportion to reflectivity increase, freshwater cultured pearls’ color was improved. Ca, Mn, Sr and other micro elements were found from ED-XRF analysis. However, changes in composition of elements were not detected. It was found that the content of Mn in freshwater cultured pearl is higher than other micro elements. From SEM analysis, aragonite's shape was shown in narce and some of the narce were condensed after heat treatment.

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