The Spectroscopic Analysis of Corrosion Products on Gold-Painted Copper-Based Bodhisattva (Guanyin) in Half Lotus Position From National Museum of China
LIU Wei1, 2, ZHANG Peng-yu1, 2, WU Na1, 2
1. The Institute of Conservation, National Museum of China, Beijing 100079, China
2. Key Scientific Research Base of Metal Conservation (National Museum of China), National Cultural Heritage Administration，Beijing 100079，China
Abstract：Copper-based artefacts are the important material manifestations of the development of ancient Chinese civilization and possess multiple types of values. Copper-based artefacts suffer from corrosion in burial and storage environments, resulting in the formation of multiple types of corrosion products on the surface of the artefacts. Different varieties of corrosion products would have different influences on the stability of the objects. The chlorine-containing corrosion is the most concerning one since it is mostly related to “bronze disease”. The “bronze disease” is a corrosion phenomenon induced by chloride ions with a high developing rate and would cause severe damage to the metallic body of copper-based artefacts. Therefore, the accurate and rapid identification of corrosion products and the determination of their stability are of great importance for copper-based artefacts. This study focuses on the corrosion products of gold-painted copper-based bodhisattva (Guanyin) in half lotus position collected in the National Museum of China. Multiple analytical methods, including macro X-ray fluorescence imaging (MA-XRF), fiber optics reflection spectroscopy (FORS), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS) and laser confocal micro Raman spectroscopy (Raman) were applied to study the composition, structure and distribution of its corrosion products. The results indicate that the corrosion products on the statue's surface mainly include copper trihydroxychlorides (at acamite and clinoatacamite) and chalconatronite. A type of copper-zinc hydroxychlorides was also identified on the statue, which was seldomly found on copper-based artefacts before. The chemical formula is calculated as Cu3.52-3.64Zn0.36-0.48(OH)6Cl2. The result provides a new reference for future researchstudy of copper-zinc hydroxychlorides. The distribution of various types of corrosion products on this statue was revealed comprehensively through the current analytical work. Copper trihydroxychlorides are mainly located at the statue's head, face, hands, legs, feet and lotus base. This study builds a scientific basis for accurately assessing the influence of “bronze disease” on the deterioration degree of the statue. The results are important for making proper preservation plans for the artefact. Combining macro and micro analysis methods could provide a new and effective way to investigate corrosion products on copper-based artefacts.
刘 薇，张鹏宇，吴 娜. 中国国家博物馆藏铜半结跏泥金观音锈蚀产物的光谱分析[J]. 光谱学与光谱分析, 2023, 43(12): 3832-3839.
LIU Wei, ZHANG Peng-yu, WU Na. The Spectroscopic Analysis of Corrosion Products on Gold-Painted Copper-Based Bodhisattva (Guanyin) in Half Lotus Position From National Museum of China. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(12): 3832-3839.
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