山东青岛“德国总督楼”旧址琉璃瓦件的釉胎损毁研究

Research on the damage to ancient glazed tiles in the former German Governor’s House in Qingdao,Shandong Province

针对青岛“德国总督楼”旧址博物馆最具代表的女儿墙绿色琉璃瓦目前出现的釉层脱落和胎体粉化等不同病变,为探索其原因,采用扫描电子显微-能谱分析、微区X射线衍射分析、热扩散系数分析、热膨胀特性分析以及界面张力分析等,确定琉璃构件釉层和胎体呈层状脱落的主要原因。结果表明:1)琉璃保护材料、釉层和胎体的热扩散、热膨胀以及各界面性能等的差异,使得含磷、铅和钙元素的腐蚀物形成于胎釉界面尤其是釉层冰裂纹延伸区域,造成胎釉界面结合强度降低,冰裂纹扩展并与胎釉结合薄弱处形成的裂缝贯通后,造成釉面呈片层状脱落;2)对于无釉胎体表面的层状剥落,含保护层胎与基体胎界面形成硫酸钙结晶带,造成界面处孔隙增加、颗粒结合降低,推测这是造成琉璃胎体呈片层状脱落的主要因素。本工作从基础性科学研究角度确定琉璃釉层和胎体层状脱落的内在原因,为进一步保护提供科学依据。

The lamellar exfoliation of the glaze layer and efflorescence of the matrix of green glazed tiles from a representative parapet sited in the Museum of the Former German Governor’s House in Qingdao,were studied using scanning electron microscopy-energy dispersive spectrometry,micro-zone X-ray diffraction,thermal diffusion coefficient analysis,thermal expansion property analysis and interface tension analysis.The results show,first,that there were differences in thermal diffusivity,thermal expansion capacity and other interfacial properties of the protective material,glaze and matrix,which caused corrosion products containing phosphorus,lead and calcium to form at the interface between the matrix and glaze,especially at the ice crack extension area of the glaze layer;thus,decreasing the interfacial bonding strength between the matrix and glaze;the ice cracks were extended and connected to the cracks formed at the weak joints between the matrix and glaze,resulting in lamellar exfoliation of the glaze.Second,a calcium sulfate crystal zone was formed between the matrix with a protective layer and the internal interface,resulting in the increase of pores at the interface and a decrease of particle bonding strength,which was speculated to be the main factor causing the lamellar exfoliation of the unglazed matrix.This research on the internal causes of lamellar exfoliation of the glaze layer and matrix could provide a scientific basis for further conservation.