铁器文物保护方法综述

铁器文物由于其性质活泼以及自身的结构缺陷,若在埋藏过程中已严重锈蚀,出土后因保护措施不到位及保存环境等因素的影响,将加速铁器文物的进一步锈蚀,因此铁器文物的保护就显得尤为重要。本文从铁器文物保护的关键步骤出发,在对铁器文物腐蚀机理、腐蚀的主要产物、分析检测技术进行分析研究的基础上,对目前铁器文物保护方法进行梳理,并对保存环境提出了具体要求,以期对铁器文物的保护工作提供一定的借鉴。     

新疆伊犁出土鎏金铜带饰的科学分析与保护

为研究、保护和修复伊犁地区出土鎏金铜带饰,在现代保护修复理念的指导下,采用金相显微镜、X射线荧光、扫描电镜及X射线能谱仪、X射线衍射等方法,对文物的主要成分、制作工艺和锈蚀产物分别进行检测分析。初步确定文物的合金成分、锈蚀产物及病害种类,并对其保存状态进行评估,制定保护方案并实施科学保护。在有效保护文物的基础上,为揭示草原地区青铜文化提供重要参考。     

深圳铁仔山古墓群出土铜器腐蚀情况研究

受深圳地区海洋气候及土壤环境影响,铁仔山古墓群出土铜器锈蚀情况严重。为了给后续的保护修复处理提供科学依据,需研究出土铜器锈蚀情况。为此,通过硝酸银定性分析、X射线荧光能谱分析、拉曼光谱分析等手段,对其表面锈蚀物进行综合分析。结果表明,该批铜器矿化严重,其锈蚀成分以孔雀石为主。其中一件铜器表面锈蚀物中含有氯磷钠铜矿,这在潮湿地区土壤环境出土的铜器中较为少见。此外,在另一件铜器表面锈蚀物中还发现疑似纳米SnO2成分。实验结果可对该批铜器的保护修复处理提供有力的理论依据和数据支持,并为深圳地区出土的其他青铜类文物的保护提供参考。     

湖北柳树沟墓群M24出土汉代薄胎铜镜的保护修复

借助超景深视频显微镜、扫描电镜、拉曼光谱仪等现代检测分析仪器对湖北柳树沟墓群出土的一件汉代薄胎残损铜镜进行了检测分析。分析包括基体的微观腐蚀形貌、合金成分、金相组织及表面锈蚀物的物相和元素组成,从而确定了此面铜镜的腐蚀程度、材质、组织结构及表面锈蚀物类型。在此基础上,采用表面清洁、点焊粘接、补全、随色及缓蚀封护等保护修复措施恢复了铜镜的器型,展现了文物原貌。     

秦汉铁器锈蚀机理探讨及保护方法研究

为了搞清铁器的锈蚀机理,为铁器文物保存提供最佳条件,通过对秦汉两代几件铁器不同部位腐蚀产物分析及不同条件下铁器锈蚀情况实验来研究古代铁器锈蚀机理及保护方法,结果发现,铁器锈蚀成分不仅十分复杂,而且同一锈蚀产物中α、β、γ三种构型的FeO.OH共存,实属罕见,同时采用新的保护方法,使铁器处于一个干燥,无氧,无盐,无水,无有害气体的最佳保护状态。     

基于拉曼光谱半定量分析的铁质文物锈层“保护能力指数”评估——以“南海Ⅰ号”沉船出水铁条为例

铁质文物锈蚀产物的稳定性对文物本体的保存与保护具有较大影响,对锈层稳定性的判断是评估铁质文物整体保存状况的关键步骤。“保护能力指数”(PAI)是锈蚀稳定相与不稳定相的含量比值,可用于评估铁质文物的锈蚀程度及腐蚀趋势。近来拉曼光谱越来越多地被用作一种半定量方法,可用于计算混合铁质文物锈蚀产物的各组分含量,因此,可利用该方法计算铁锈的PAI值。本研究利用激光拉曼光谱方法,并结合大幅面X射线荧光成像等多种方法手段,以“南海Ⅰ号”出水一件铁条文物为例,对其锈蚀产物进行半定量分析,并计算出锈蚀PAI值。结果表明,铁条主要包含α-FeOOH、γ-FeOOH、β-FeOOH及Fe₃O₄四种锈蚀产物,不同种类的锈蚀在内外层的分布规律有一定差异。铁条锈蚀PAI值波动范围较大,最低为0.34,最高为20.38,PAI值主要分布于1～10之间。内外锈层的PAI值不同：外层锈蚀PAI值相对较高,说明锈蚀较为稳定;层状剥离面锈蚀PAI值<1,表明锈蚀非常不稳定;内层锈蚀PAI值最低为0.73,说明存在不稳定锈蚀。铁质文物锈蚀产物PAI值为科学评估文物的保存状况提...     

重庆忠县洞天堡墓地出土西汉青铜钫的腐蚀研究

为了解重庆洞天堡墓地出土青铜器的保存状况、腐蚀产物种类和埋藏环境特征等,并探索其锈蚀成因,为即将进行的保护修复工作提供科学的依据,利用三维视频显微镜、激光共聚焦拉曼光谱仪和扫描电子显微镜等对重庆忠县洞天堡墓地出土青铜钫残片进行微观形貌观察和锈蚀物结构成分分析,并利用X射线荧光和微生物分析技术对青铜钫附着土壤进行成分和微生物分析。结果表明:该青铜钫锈蚀物含孔雀石、白铅矿、铅钒、磷氯铅矿、砷铅矿和赤铜矿等;外层锈蚀存在磷和氯元素富集现象;土壤中的磷、硫和氯等元素向青铜器迁移,青铜器中铜、锡和铅元素因腐蚀向土壤中流失;附着土富含多种真菌类微生物,促进了磷氯铅矿和砷铅矿的形成。     

铁仔山古墓群出土铁器腐蚀病害与机理分析

深圳铁仔山古墓群出土铁器由于受到出土前的埋藏环境、库房保存条件等因素的影响,以及出土后未及时采取有效的保护措施,致使铁器锈蚀严重。为了延长这些铁质文物的寿命,减少其腐蚀损毁,本工作采用显微镜观察、密度法判断、硝酸银定性分析、X射线衍射和X射线荧光能谱等分析方法对铁器锈蚀状况进行了综合分析。结果表明：铁仔山古墓群出土铁器矿化严重,锈蚀产物主要包括针铁矿、纤铁矿、赤铁矿、大量黏土矿物及可溶盐。通过分析比较这些锈蚀产物及铁器锈蚀程度,对铁器锈蚀机理进行了分析,得知铁仔山出土铁器在埋藏时已受到严重的腐蚀,出土后未及时清除表面的污染物和有害锈及脱除可溶盐,加速了铁器文物的进一步腐蚀,加之保存环境湿度较高,致使空气中的水分透过锈层孔隙在未锈的铁质部分凝结,导致土壤中的有害成分继续危害铁器,大气中的尘埃粒子沉降到器物表面,因吸湿作用使铁器表面形成水膜,造成有利于腐蚀的环境。多种因素协同作用,使铁器文物的腐蚀加剧。本工作对这批铁器文物的进一步保护修复提供了理论依据和数据支持,也为沿海地区铁器文物的保护提供了参考。     

作册般鼋的分析与保护

作册般鼋是中国国家博物馆新征集文物。保护前经X光探伤检测发现器物背部有4行铭文。为了将文物的面貌如实还原,以分析检测为基础,运用了局部锈蚀软化、机械除锈相结合的方法对该器物进行科学保护。     

六朝初期铜鎏金铺首衔环保护与研究

为了对一件六朝初期的铜鎏金铺首衔环进行保护,运用X光透视、扫描电镜、红外光谱等仪器对其鎏金层和腐蚀产物进行了分析。通过扫描电镜能谱分析得知鎏金层含有较高的金元素并有部分的汞元素,由于汞元素的存在,进一步验证了其为鎏金器。根据浅绿色锈蚀样品的红外光谱分析,浅绿色锈蚀是有害锈氯铜矿(Cu2(OH)3Cl),必须对其进行除氯处理。而覆盖鎏金层的绿色锈蚀在扫描电镜能谱分析中所示氯离子含量并不明显,并根据红外光谱的分析确认其为无害锈孔雀石(Cu(OH)2.CuCO3),但其影响了铺首鎏金层艺术欣赏价值,需采取措施将其清理,对位于铺首背面的则给予保留。保护修复过程中,尝试了先用去离子水浸渍填充鎏金文物毛细管后,再用强酸性离子交换树脂快速处理覆盖鎏金层的绿色锈蚀,达到了预期效果。实践证明该方法可以有效地把铺首左面鎏金层清理出来。     

中国钱币博物馆部分陈列银币、铜币的腐蚀产物及成因研究

为探讨部分陈列银币、铜币腐蚀产物及其成因,采用三维视频显微镜、扫描电镜-能谱(SEM-EDS)、X射线荧光(XRF)、X射线衍射(XRD)等方法,对中国钱币博物馆部分遭受腐蚀的展陈钱币的腐蚀产物进行了分析,并通过红外光谱(FT-IR)对展陈材料进行了分析,最后对硫的来源进行了初步分析。结果表明,银币和铜币的腐蚀产物均含有硫化物,银币(银铤)的腐蚀产物为硫化银,铜币的腐蚀产物中主要为铜的硫化物,此外还含有铜的氧化物。经分析,展柜中的黏合剂氯丁胶在光照和较高温湿度条件下能分解并释放出硫化氢气体,因而初步判断银币或铜币的腐蚀产物是由于展柜内材料产生的硫化氢与银币或铜币反应生成。     

X-RAY FLUORESCENCE AND DENSITY MEASUREMENTS ON SURFACE-TREATED ROMAN SILVER COINS*

Some 630 Roman silver coins excavated at Augusta Raurica (Switzerland) have been analysed by non-destructive X-ray fluorescence and X-ray diffraction. Furthermore, the density and the weight have been determined. The measured average density of plated and massive depletion-silvered coins is lower than the density calculated from the chemical composition, whereas massive coins display equal values for both of the densities. Based on experimental X-ray investigations of modern silver (tempering, acid treatment, production of corrosion layers), the nature of corrosion products on silver, their impact on surface analysis, and aspects of wearing-off by circulation are briefly discussed.     

Metallurgical study on some Sasanian silver coins in Sistan Museum

Elemental analyses and microstructural studies of historical metal artifacts provide researchers with invaluable and priceless information about metal extraction technology and the procedure of creating artifacts. In addition, the information is helpful for knowing about the metallurgical processes of the artifacts. This study was conducted by a microscopic examination and elemental analyses of seven Sasanian silver coins preserved in the Sistan Anthropology Museum, Iran. For the purpose of this study, three methods were employed: first, the proton induced X-ray emission microanalysis (micro-PIXE), to determine the main and trace elements of the coins; second, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), to perform elemental analysis to identify impurities of the metal; and third, microstructural analysis of the coins which was carried out with an optical microscope (OM). The elemental analyses identified Ca, Cu, Ag, Au, and Pb in the coins. The high quantity of Ag in samples validated the application of advanced and accurate cupellation technology for refining silver and separating impurities from raw ore. The gold concentration in the coins indicated the use of non-galena ore for silver extraction. Additionally, the microstructural analyses of samples pointed to the application of thermo-mechanical processes on coins.     

DETECTION OF NEAR-SURFACE SILVER ENRICHMENT ON ROMAN IMPERIAL SILVER COINS BY X-RAY SPECTRAL ANALYSIS*

A collection of 218 Roman imperial silver coins, covering three centuries, was analysed non-destructively by two variants of X-ray spectral analysis. Electron beam excitation and energy-dispersive spectrometry was used for the analysis of the uppermost thin layer (3 μm) of each coin, while X-ray tube excitation and wavelength-dispersive spectrometry was applied for the analysis of thicker layers (30 μm), Ag and Cu as major constituents and 18 minor elements were determined quantitatively. Comparing the silver content of the obverse and the reverse of a coin, inhomogeneities could be identified. By comparison of the silver content of the upper thin and the thick surface layers, near-surface silver enrichment could be detected. Inhomogeneities and enrichments increase in the second and more so in the third century. A large scatter of the silver content and silver enrichment for coins of the same emperor was attributed to varying abrasion of Ag-enriched layers of the individual coins during decades of circulation.     

北宋和南宋青铜钱币对比分析研究

宋代是我国钱币的一个大发展时期,宋代钱币在我国钱币史上占有极其重要的地位.为了解南、北宋钱币的成分、显微结构的差异对铸币保存状况的影响,通过显微镜观察、合金成分分析、显微结构分析,对南宋和北宋各21枚钱币的保存状况进行了对比分析研究,以了解这42枚钱币的锈蚀状况、锈蚀原因,以及成分、显微结构的差异对铸币保存状况的影响.同时在分析研究的过程中,对北宋、南宋钱币的合金成分、铸造工艺进行了对比研究.研究结果表明,南宋钱币的保存状况比北宋的差一些,合金成分及显微结构的差异,是导致保存状况不同的重要原因.这些钱币主要是由铜、锡、铅铸造而成,分析结果进一步证实北宋钱币合金成分比较稳定,成分配比比较科学.而南宋成分数据比较分散,早期铜、锡含量较高,铅含量较低,晚期铜、锡含量较低,铅含量明显增高,合金品质大大降低.本研究可为了解当时的科学技术、社会经济形态进一步提供基本信息.     

QUANTITATIVE ANALYSIS OF COPPER-TIN BRONZES BY MEANS OF GLOW DISCHARGE OPTICAL EMISSION SPECTROMETRY

Glow discharge optical emission spectrometry (GDOES) has been used for obtaining calibration curves for copper, tin, lead, silver, antimony, arsenic, zinc and iron from standards including copper-base alloys (Cu 61.33-99.95%) and from bronze Punic coins. The GDOES results were calibrated using atomic absorption spectroscopy with inductively coupled plasma atomization (ICPAAS) to analyse the standards and coins. For all these materials, the results show that via GDOES it is possible to obtain reliable and reproducible calibration curves for copper, tin, lead, zinc and iron with a linear behaviour as a function of the content. The quantitative GDOES and ICPAAS data for the coins have been also compared with those obtained via X-ray fluorescence (XRF) and it is shown that GDOES, ICPAAS and XRF agree well with one another considering that the bronze coins are inhomogeneous to some degree. As an example of GDOES analytical features, a depth concentration profile through a thin bronze patina is shown and briefly discussed.     

NON-DESTRUCTIVE RADIOISOTOPE X-RAY FLUORESCENCE ANALYSIS OF OLD SILVER COINS

The paper presents the results of a feasibility study of the application of X-ray fluorescence analysis to nondestructive analysis of coins. Radioisotope sources ⁵⁵Fe, ²⁴¹Am, ¹⁰⁹Cd and ²³⁸Pu were used for excitation and a Si/Li detector with a multichannel analyser for the measurement of characteristic X-ray lines. Silver and copper in Polish renaissance coins have been analysed. Analysis using Ag K and Ag L lines allows one to distinguish between blanched and unblanched coins. The accuracy of the silver determination using Ag K X-rays is claimed to be ± 0.5% Ag for homogenous coins and ± 1.0% Ag for blanched but well-preserved uncorroded coins.     

Chronological discrimination of silver coins based on inter‐elemental ratios using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS)

This paper details the application of a statistical method for the chronological discrimination of silver coins using counts per second trace elemental, inter‐elemental ratios. The statistical method described is based on a method that has been applied to similar archaeological materials to determine their provenance. The method makes use of the inter‐element association patterns of multi‐element analytical data determined using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). The majority of the 266 coins analysed for this study have already been successfully identified by their mint markings. The data from LA‐ICP‐MS analyses, together with what is known about the coins through visual identification, were used to discriminate the reigning sovereign, and in the case of Mexico, the year of minting, of individual coins within the elemental fingerprint of different mints. Subsequently, unidentified coins can be placed in the confusion matrix, and their trace element information used to identify their year of minting when compared with other, identified coins from the same mint. The interpretational statistical technique linear discriminant analysis (LDA) was used to explore an identification of year of minting of coins that have previously not been identified by other means based on a statistical comparison against a database of compositional analysis of silver coins of known year of minting.     

ROME AND THE EAST. PRODUCTION OF ROMAN PROVINCIAL SILVER COINAGE FOR CAESAREA IN CAPPADOCIA UNDER VESPASIAN, AD 69–79

During the first three centuries AD several eastern provinces of the Roman empire produced silver coinages of specifically local denominations and types. It has been claimed that at certain periods the mint of Rome was employed to strike some of these coinages, rather than the provincial mints to which the coins are traditionally attributed. This claim is based mainly on stylistic observations, but because style is regarded as subjective, some other form of evidence to support these observations is desirable. In this paper three types of coin are submitted to metallurgical analysis: silver denarii struck at Rome; Roman-style provincial silver coinage; and 'local'style provincial silver coinage. The aim is to discover whether the Rome-style and 'local'style coins have different trace element profiles, and whether these might indicate different ore sources or refining techniques. The results are then compared with Roman denarii to see whether there are any similarities between the denarii and the Rome-style provincial silver coins.     

A Trial PIXE/PIGME analysis of Pre-Islamic Arabian Coinage

Eight previously published (1) pre-Islamic coins minted in Arabia were subjected to non-destructive ion beam analysis by Proton Induced X-Ray (PIXE) and Gamma-Ray Emission (PIGME) at Lucas Heights. The results (2) were interpreted using Principal Components Analysis (PCA). The relative X-ray intensities of fifteen elements, supplemented with additional L alpha lines for two of the elements, were extracted for this analysis. PCA (results appended) was first carried out on the whole dataset where the distinctive high iron and nickel composition of two coins (331 and 335) resulted in their position as outliers. A second analysis of the subset of silver coins showed the compositional similarity between four coins (44, 222, 226, 359) and distinguished two separate outliers. One of these (369) has a high lead and tin content while the other (354) has a greater proportion of elements present as impurities (?) including iron and nickel. The two outliers and the relatively homogenous compositions of the group of four coins suggest that three compositional types of silver coinage are represented in the dataset: 1. a relatively silver-rich group of four coins; 2. silver coins debased with lead; and 3. silver coins debased with iron and nickel.