重庆地区露天石刻早期封护材料老化产物及其影响研究

发布时间：2018-06-13 14:44

  本文选题：露天文物 + 石质文物　； 参考：《光谱学与光谱分析》2017年10期

【摘要】：重庆市市委会办公大楼旧址前有一组露天存放的清代砂岩石狮子,表面覆盖着黑色硬壳状物质,发生大面积脱落,起翘和卷曲。为了揭示黑色硬壳状结构组成,研究其形成过程及对文物产生的影响,利用环境扫描电子显微镜(SEM),X-射线衍射仪(XRD),X-射线荧光光谱仪(XRF),傅里叶变换红外光谱仪(FTIR)和X-射线光电子能谱(XPS)对黑色硬壳及文物表层砂岩样品进行了检测分析研究。结果发现:黑色硬壳断面Mapping元素分布图显示其分为底漆层,中间层和表层,系石刻早期封护层的老化产物;中间层含有立德粉(硫化锌和硫酸钡),黑色外观源于表层中含铅颜料(铅白)变色形成黑色硫化铅及树脂碳化所致;红外光谱与光电子能谱显示出黑色硬壳中含有强的羟基(—OH)特征峰,说明封护层中有机物老化后形成了大量羟基,从而增强了自身亲水性,造成易吸水溶胀与干燥收缩情况,导致大面积脱落,起翘和卷曲现象;黑色硬壳起翘和卷曲部位与下层石刻表面之间形成了易于积水的微空隙,能够聚集雨水中的有害物质,造成石刻表层岩石发生腐蚀,例如黑色硬壳背面及下层岩石表面中高含量硬石膏(CaSO4),经生水化作用后转化为石膏(CaSO4·2H2O),发生体积膨胀造成岩石表面松动和酥粉。因此,当露天文物表面上封护层已老化时,及时地进行清除是十分必要的。
[Abstract]:In front of the old office building of Chongqing Municipal Committee, there was a group of open storage stone lions of the Qing Dynasty, covered with black hard shell material, with large area falling off, warping and curling. In order to reveal the composition of the black hard shell structure, the formation process and its influence on the cultural relics were studied. The detection and analysis of black hard shell and surface sandstone samples were carried out by means of environmental scanning electron microscope (SEM) and XRDX X ray diffractometer (XRF), Fourier transform infrared spectroscopy (FTIR) and X- ray photoelectron spectroscopy (XPS). The results show that the mapping element distribution of black hard shell section is divided into primer layer, middle layer and surface layer, which are the aging products of the early seal layer of stone carving. The intermediate layer contains lithopone (zinc sulphide and barium sulfate), and the black appearance is caused by the discoloration of lead pigment (lead white) in the surface layer to form black lead sulfide and resin carbonization. Infrared spectrum and photoelectron spectroscopy show that the black shell contains strong hydroxyl group (OH) characteristic peak, which indicates that a large number of hydroxyl groups are formed after the organic matter in the seal layer is aged, thus enhancing its hydrophilicity, resulting in easy water absorption swelling and drying shrinkage. Leading to the phenomenon of large area shedding, warping and curling, and the formation of microvoids between the parts of the black hard shells and the surface of the lower stone carvings, which can accumulate the harmful substances in the Rain Water and cause the corrosion of the rocks on the surface of the stone carvings. For example, the high content of anhydrite CaSO _ 4H _ 4 in the back of the black hard shell and the rock surface of the lower layer is converted into gypsum caso _ 4 _ 2H _ 2O after raw hydration, and volume expansion results in the loosening of the rock surface and the fining powder. Therefore, it is necessary to remove the protective layer on the surface of open-air relics in time when it has aged.
【作者单位】： 陕西师范大学材料科学与工程学院;重庆市文化遗产研究院;
【基金】：国家自然科学基金(51403121) 陕西师范大学中央高校基本科研业务费项目(GK201501002,GK201505080,GK201503037)资助
【分类号】：K879.3;O657
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本文编号：2014373