Ancient Iron Artifacts Research Articles

Construction and Performance of Superhydrophobic Surfaces for Rusted Iron Artifacts

Ancient iron artifacts need to be protected with a rust layer, often stabilized by tannic acid corrosion inhibition. In humid environments, water vapor could slowly penetrate and trigger galvanic corrosion of metal artefacts. Sealing treatments are generally applied to the artefact surface to isolate water and enhance its corrosion resistance. Superhydrophobic modifications could effectively block the penetration of moisture into the interior of the artefact and provide a nice water barrier. Stearic acid with tannic acid inhibition treatment creates a superhydrophobic protective layer on the surface of rusted iron artifacts and enhances corrosion resistance effectively. Various scientific analyses and testing methods are used in this paper to evaluate the corrosion resistance of rusted surfaces after superhydrophobic modification and investigate the reaction mechanisms. The results indicate that the contact angle of the rusted surface after corrosion inhibition by tannic acid and modified by stearic acid is increased to 152.2°, which means the superhydrophobic protective layer has been successfully constructed. The C/Fe ratio of the rusted surface is increased from 0.21 to 2.10, and the characteristic diffraction peaks of O1s and Fe 2p3/2 shift toward higher binding energy. Stearic acid is combined with the corrosion product layer by chemical bonding. Chelation between rust products, tannic acid, and steric acid is effective, and the chelate is chemically stable. The superhydrophobic surface forms a lamellar wax-like layer as an air barrier to isolate liquid water, resulting in a significant decrease in corrosion current and an increase in Warburg impedance to 217.9 times the original state, with a protection efficiency of 88.3%. Tannic acid corrosion inhibition and stearic acid superhydrophobic modification have an excellent synergistic protective effect on improving the corrosion resistance of iron artifacts, resulting in better corrosion resistance of iron artifact materials. The research provides new ideas and references for the protection of ancient iron artifacts sealing.

A method of conserving ancient iron artefacts retrieved from shipwrecks using a combination of silane self-assembled monolayers and wax coating

Iron artefacts corrode severely in a marine environment, and require further conservation after retrieval. This research proposes a novel conservation method, based on a bi-layered concept: a thin silane self-assembled monolayer serving as nano-scale barrier, covered by a thicker waxlayer, which is applied by dipping the object into a suitable solution. An accelerated corrosion test was performed, using modern cast iron and steel samples, and repeated on archaeological wrought iron artefacts retrieved from shipwrecks. This protection, which can be easily applied, was found to improve the corrosion resistance of the artefacts.

Iron isotopes as a potential tool for ancient iron metals tracing

Provenance studies of iron artefacts have become an important topic in archaeology to better understand the socio-economic organization of ancient societies. Elemental and isotopic tracing methods used so far for iron metal provenance studies showed some limitations, and the development of new additional tracers are needed. Since the last decade, the rise of cutting edge analytical techniques allows for the development of new isotopic tools for this purpose. The present study explores for the first time the use of iron isotopes analyses as a potential method for ancient iron metal tracing. Ore, slag and metal samples from two experimental reconstitutions of iron ore reduction by bloomery process were collected. Their Fe isotope compositions were measured by Multi Collector – Inductively Coupled Plasma – Mass Spectrometry (MC-ICP-MS) to assess the possible impact of smelting on the Fe isotope composition of the metal produced. Our results show that the iron isotope compositions of the slag and metal are for 8 out of 9 samples analyzed undistinguishable from that of the starting ores. This suggests that overall, no significant Fe isotope fractionation occurs along the chaîne opératoire of iron bars production, even if slight isotopic differences might be found in blooms before refinement. This fact, combined with the natural isotopic variability of iron ores, as reported in the literature, may allow the use of Fe isotopes as a relevant tracer for archaeological iron metals. This new tracing approach offers many perspectives for provenance studies. The combination of elemental and Fe isotope analyses should thus be useful to validate origin hypotheses of ancient iron artefacts.

The meteoritic origin of Tutankhamun's iron dagger blade

AbstractScholars have long discussed the introduction and spread of iron metallurgy in different civilizations. The sporadic use of iron has been reported in the Eastern Mediterranean area from the late Neolithic period to the Bronze Age. Despite the rare existence of smelted iron, it is generally assumed that early iron objects were produced from meteoritic iron. Nevertheless, the methods of working the metal, its use, and diffusion are contentious issues compromised by lack of detailed analysis. Since its discovery in 1925, the meteoritic origin of the iron dagger blade from the sarcophagus of the ancient Egyptian King Tutankhamun (14th C. BCE) has been the subject of debate and previous analyses yielded controversial results. We show that the composition of the blade (Fe plus 10.8 wt% Ni and 0.58 wt% Co), accurately determined through portable x‐ray fluorescence spectrometry, strongly supports its meteoritic origin. In agreement with recent results of metallographic analysis of ancient iron artifacts from Gerzeh, our study confirms that ancient Egyptians attributed great value to meteoritic iron for the production of precious objects. Moreover, the high manufacturing quality of Tutankhamun's dagger blade, in comparison with other simple‐shaped meteoritic iron artifacts, suggests a significant mastery of ironworking in Tutankhamun's time.

First examination of slag inclusions in medieval armours by confocal SR-µ-XRF and LA-ICP-MS

To elucidate the origin of armours supposed to be from Lombardy according to art-historians, the very small Slag Inclusions entrapped in the metallic matrix were analysed on the samples taken on armours. This paper presents the analytical protocol, based on the coupling of LA-ICP-MS and confocal SR-µ-XRF (confocal Micro-X-ray fluorescence under Synchrotron Radiation) developed to obtain trace element information from this kind of inclusion. Confocal SR-µ-XRF has been applied to inclusions of ancient iron artefacts for the first time. The reliability and reproducibility of the procedure developed for the trace elements quantifying have been checked by a comparison of the results obtained by LA-ICP-MS and by confocal SR-µ-XRF. Our first results allow us to draw some preliminary observations on the origin of the samples.

Simple Pretreatment Method Development for Iron and Calcium Carbonate Samples

Since iron artifacts generally contain trace amounts of carbon, an iron sample needs to be relatively large, as compared to other materials, and a specially designed combustion system is required. An elemental analyzer (EA) was used for the combustion of iron without any special chemical treatment. CO2 gas with 1 mg of carbon was obtained from the combustion of an iron artifact by using an EA and reduced to graphite for accelerator mass spectrometry (AMS) measurement. In this work, AMS dating results done at the Korea Institute of Geoscience and Mineral Resources (KIGAM) for several ancient iron artifacts are presented and compared with independently estimated ages. This method was found to be useful for the pretreatment of iron artifacts that contained >0.1% carbon. A simple pretreatment method using an EA was also applied to calcium carbonate (CaCO3) samples. Samples were preheated overnight at 100–300 °C, without any special chemical treatment. This removed modern CO2 contamination and the background level decreased to a comparable value measured in samples treated with phosphoric acid under vacuum.

Electrochemical study of indoor atmospheric corrosion layers formed on ancient iron artefacts

Several indoor atmospheric corrosion layers (0–800 years old) were selected from different localisations in France. Each sample was scrapped from its iron substrate. The resulting powder was mixed with graphite in appropriate proportions and the mixture was pressed onto a stainless steel grid to constitute a composite electrode. The electrochemical responses of the different samples were recorded under galvanostatic regulation, in a near-neutral pH-buffered NaCl solution at 25 °C. The E– t reduction curves allowed the determination of two characteristic parameters, E τ/2 , the potential value obtained at half the transition time, and Q τ , the coulombic charge obtained at the end of the reduction. The diminution of E τ/2 and Q τ with the age of the corrosion layer showed that the “reduction reactivity” decreases with time, suggesting a progressive stabilisation of the corrosion layer. In a second part of the work, we synthesised several common ferric or ferrous/ferric products (goethite, lepidocrocite, magnetite, maghemite, ferrihydrite) and compared their reduction responses (product alone or mixture of 2 or 3 products) to those of corrosion samples.

AMS Radiocarbon Dating of Ancient Iron Artifacts: A New Carbon Extraction Method in Use at LLNL

A new sealed double tube combustion method was developed at Lawrence Livermore National Laboratory (LLNL) to extract carbon from modern steels and ancient iron artifacts. Iron samples were chemically pretreated with 10% nitric acid, vacuum sealed in 6 mm quartz tubes with CuO, vacuum sealed again inside 9 mm quartz tubes, and combusted at 1000 °C for a minimum of 10 hr. The resulting CO2 was graphitized routinely using hydrogen reduction (Vogel et al. 1989). After the initial phase of development, carbon yields of 100% were consistently obtained. The activities of two modern high carbon steels (treated as process blanks, manufactured using only coal as the carbon source) were determined to be 0.0077 ± 0.0009 (n = 12, ± 1 σ) for a 1.3% C steel and 0.0090 ± 0.0038 (n = 12, ± 1 σ) for a 1.9% C steel, indicating that very little contamination is introduced during the sample preparation process. Since the Iron Age began less than 5000 years ago, these background uncertainties should introduce errors of no more than ±30 years to the radiocarbon ages of actual artifacts. Two ancient iron artifacts of known date were analyzed and demonstrate that the new methodology can be used to obtain the correct date of manufacture for iron objects, provided that they are made exclusively using charcoal that was contemporaneous with the manufacture of the artifact. Since only 1 mg of carbon is required for accelerator mass spectrometry (AMS), very small iron samples can now be analyzed (50 mg of a 2.0% C iron or 1 g of a 0.1% C iron). We anticipate that this methodology will be particularly useful to archeologists who currently have to rely on context to date iron artifacts.

Pretreatment of Iron Artifacts at SNU-AMS

We present the current status of accelerator mass spectrometry (AMS) dating of iron artifacts at Seoul National University (SNU). In ancient iron production, charcoal was widely used as carbon for the smelting process, whereas coal is used in modern times. If reliable data could be obtained from carbon by using AMS, ancient iron artifacts could be traced to their production age. In normal acid treatment, it is not easy to extract carbon due to its colloidal property. The negative charge property of the carbon colloid, however, makes it possible for it to be precipitated with positive ions by dissolving the iron chemically. An extraction yield of the carbon incorporated in modern cast iron of about 70% is attained. More refined methods to increase the extraction rate are under progress for archaeological applications.

Radiocarbon Dating Study of Ancient Iron Artifacts with Accelerator Mass Spectrometry.

Radiocarbon Dating Study of Ancient Iron Artifacts with Accelerator Mass Spectrometry.

Application of low-pressure hydrogen plasma to the conservation of ancient iron artifacts

A new method based on the application of lowpressure hydrogen plasma has been developed for the restoration of iron artifacts. It efficiently removes chlorides and in this way essentially prevents any significant post-corrosion. The treatment temperatures of less than 400°C do not introduce any irreversible changes in the wrought iron, preserving its original composition, structure inclusions and morphology, which contain important information on the origin and manufacturing methods of the artifact. The experience obtained during the treatment of more than 50 artifacts showed that it is much easier for the conservator to uncover the original surface of the artifacts which were pretreated in the plasma as compared to those treated in the conventional way.

Application of Low-Pressure Hydrogen Plasma to the Conservation of Ancient Iron Artifacts

Application of Low-Pressure Hydrogen Plasma to the Conservation of Ancient Iron Artifacts