一件中国国家博物馆馆藏铜雕塑锈蚀产物的分析研究

Research on the corrosion products of a copper sculpture in the collections of the National Museum of China

铜雕塑作为现代艺术品因其历史价值、文化价值、审美价值、科技价值和时代价值被越来越多的博物馆收藏。经过岁月的洗礼,雕塑上有时也会出现锈蚀产物,锈蚀产物或影响艺术品的美感或进一步损害雕塑,因此需要对锈蚀产物进行鉴别,然后采取适合的方法将其去除。为此,通过超景深三维视频显微观察、扫描电子显微镜-能谱仪、显微激光拉曼光谱和傅立叶变换显微红外光谱对一件中国国家博物馆馆藏铜雕塑锈蚀产物进行取样分析。能谱结果表明该锈蚀产物中没有氯离子,再结合拉曼光谱和显微红外光谱结果可以确定锈蚀产物是蓝铜钠石[Na_(2)Cu(CO_(3))_(2)·3H_(2)O]和含有钠离子和氧离子的水合甲酸铜[Cu_(4)Na_(4)O(HCOO)_(8)(OH)_(2)·4H_(2)O],这种铜锈蚀产物在国内报道较少。为防止它们进一步腐蚀和损害雕塑,选择使用物理方法将锈蚀产物清除。科学的检测方法和分析手段为铜雕塑保护方案的制定提供了重要信息支撑和理论依据。

Sculptures are not only a historical record of social development,the display of people’s aesthetic sentiment and spiritual life,but also a symbol and carrier of advanced cultures.As modern artworks,copper sculptures have been collected by more and more museums due to their historical,cultural,aesthetic,technological and era value.Corrosion products may sometimes be produced on sculptures after years,which may affect the beauty of artworks or further damage sculptures.Therefore,it is necessary to identify corrosion products and then take suitable methods to remove them.The corrosion products includes not only inorganic copper salts,but also some organic copper salts caused by volatile organic compounds.This complexity poses great challenges for analytical detection and result analysis.Corrosion products of a copper sculpture collected by the National Museum of China were analyzed using several methods,including 3D video ultra-depth-of-field microscopy,scanning electron microscopy coupled with energy dispersive X-ray spectrometry(SEM-EDS),micro-Raman spectrometry and microscopic Fourier transform infrared(micro-FTIR)spectrometry.The corrosion products observed under an optical microscope are mainly light blue and blue.The SEM-EDS results show that there is no chloride element in the corrosion products of the copper sculptures.Accordig to the results of Raman and micro-FTIR spectrometry,it can be determined that the corrosion products are chalconatronite[Na_(2)Cu(CO_(3))_(2)·3H_(2)O]and sodium copper formate hydroxide oxide hydrate[Cu_(4)Na_(4)O(HCOO)_(8)(OH)_(2)·4H_(2)O]which is rarely seen in domestic reports on copper corrosion products.It is of great significance for understanding the corrosion products of copper cultural relics.Scientific detection methods and analysis results provide important information and guidance for investigating the causes of formation of corrosion products and making proposals for the conservation of copper sculptures.Analysis of the preservation conditions and storage environment of the copper sculpture revealed that the sculptures was generally displayed or stored without independent cabinet.On the copper sculpture,there are stains which may be residues from cleaning.It is known that Cu_(4)Na_(4)O(HCOO)_(8)(OH)_(2)·4H_(2)O can be synthesized by storing chalconatronite in a desiccator with a formaldehyde/formic acid-rich atmosphere.Therefore,it can also be inferred that formaldehyde/formic acid exists in the exhibition or storage environment of the sculpture.The volatile organic compounds in the collection environment mainly come from the release of building materials and wood materials.In the warehouse,the bottom of the cabinet where the copper sculpture is stored is covered with wooden boards,which are the source of the release of volatile organic compounds such as formic acid and acetic acid.The above are reasons for the formation of corrosion products on the sculpture.In order to prevent the small corrosion produts from further corroding and damaging the sculpture,physical methods will be used to remove the corrosion products.In addition to keeping clean and controlling the temperatures and humidity inside and outside the storage places of copper sculptures,they should be kept away from acidic substances and items such as wooden objects that release acidic gases easily,so as to prevent harmful gases from adversely affecting cultural relics.