馆藏“汉并天下”瓦当表面析出物的光谱法分析

Spectrometric Analysis of Crystalline Efflorescence in one Han Dynasity Eaves Tile

本文采用激光拉曼光谱仪(Raman)、傅立叶变换显微红外光谱仪(FT-IR)、X射线衍射仪(XRD),结合三维视频显微镜、场发射环境扫描电子显微镜-能谱仪(SEM-EDS),对中国国家博物馆馆藏汉代瓦当基体及其表面析出物进行分析鉴定。通过显微观察发现瓦当表面析出物主要有两种,即黄白色块状物和由非常细小的白色绒毛状物质组成的针状物。通过四种仪器分析结果相互印证,确定黄白色块状物的主要成分为碳酸钙,白色针状物的主要成分为Ca_(3)(CH_(3)COO)_(3)Cl(NO_(3))_(2)·6H_(2)O,一种陶质文物在酸性环境中形成的有机酸钙盐。建议将陶质文物从酸性环境中移出并进行脱盐处理,储存在无酸环境中。光谱分析法可为陶质文物表面析出物成分的确定提供强有力的技术支持,其科学的检测分析数据对探究文物病害产生的原因以及文物保护修复方案的制定提供必要且充分的保障。

Crystalline efflorescence was found on some eaves tiles collection in National Museum of China.In order to recognize the composition of the salts,some sample was collected from one piece of eaves tile.3D video microscope and scanning electron microscopy were applied to observe its morphology,the crystalline salt included yellow-white powder and white fibrous crystals.Raman spectroscopy,infrared spectroscopy and X-ray diffraction were used to identify the two kinds of salts.According to the mutual confirmation of different spectral analysis results,the main composition of yellow-white powder was calcium carbonate,while the main composition of fibrous crystals was thecotrichite.Thecotrichite is an efflorescent salt occurring on surfaces of porous calcareous objects stored in wooden cabinets.Those wooden cabinets are easily emitting amounts of acetic acid vapor.Therefore,it is recommended that the eaves tile be removed from the wooden cabinet,desalinated,and stored in an acid-free environment.The spectroscopic method can provide technical support for identification of ancient pottery crystal salt composition.The results provide scientific data guidance for the establishment of the conservation and rehabilitation programme.