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Iron artifacts undergo complex corrosion processes, depending on the burial environment. Understanding the formation mechanism of corrosion products is crucial for preservation of artifacts and helps design strategies for future iron artifacts protection. Mössbauer spectroscopy was primarily utilized in this work to analyze the corrosion products formed on iron artifacts. The corrosion products were identified as consisting of goethite, lepidocrocite, magnetite, and maghemite. Low-temperature Mössbauer spectroscopy was performed for the accurate identification and quantitative analysis of superparamagnetic iron corrosion products. The results indicated that the surface corrosion products mainly consist of goethite and superparamagnetic goethite, with small amounts of lepidocrocite, magnetite, and/or maghemite. A cross-sectional analysis of the corrosion layers on an artifact was performed to better understand the corrosion products and their formation mechanisms. The products formed in different sections (metal, intermediate, and surface) of the corrosion layers on the iron artifact were identified, and a corrosion mechanism was proposed. The intermediate layer adjacent to the metal contains magnetite, maghemite, and lepidocrocite. The results presented in this study provide a deeper understanding of the iron corrosion process, laying a solid foundation for the development of an effective strategy for preserving 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.

Up until now, a few artifacts made of meteoritic iron have been discovered worldwide, though none in Morocco. The number of these objects has rarely been verified, as museums generally do not allow artifacts to be tested, and they are often confused with common smelted objects of the Iron Age. In this work, portable X-ray fluorescence (pXRF) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) have been used to analyze three iron dagger blades recovered in two localities near Imilchil and Missour in Morocco. The composition of one blade (7.2 wt% Ni and 1.1 wt% Co) strongly supports its meteoritic origin, whereas it was not so for the other two ones. The results of this work provide the first case of the exploitation of meteoritic iron as a metal source in Morocco.

Iron palaeometallurgy was carried out on three artefacts, classified as nails and excavated from the archaeological site of Loiola (La Arboleda, Biscay, northern Spain), to investigate Roman manufacturing techniques. Energy Dispersive Spectroscopy (EDS) coupled with Environmental Scanning Electron Microscopy (ESEM) and micro-Raman spectroscopy were used to obtain elemental composition and structural characterization of mineral phases. Metallurgical properties and crystallographic texture were studied by combining microscopic methods such as optical microscopy (OM), Electron Backscatter Diffraction realized in environmental mode (EBSD) and measurements of local Vickers microhardness. The three artefacts had different microstructures, distinguished by a large gradient of carbon content, although important segregations (inclusions) were observed in all of them. Two pearlite-rich artefacts showed a high density of structural defects (geometrically necessary dislocations and large crystallographic orientation gradients in pearlitic ferrite, curved pearlitic cementite) resulting from a high level of plastic deformation that occurred during the manufacturing process. The third artefact consisted of pure ferrite without structural defects. This one was clearly manufactured differently from the two others, so it probably had another functionality.

The current study was focused on Fe oxyhydroxides from the north-western part of the East-European platform. Modern-day Fe oxyhydroxides of bacterial origin demonstrate an enhanced concentration of rare earth elements (up to 1200 ppm), compared to samples without iron bacteria. The 143 Nd/ 144 Nd ratio in bacterial Fe oxyhydroxide has the value from 0.511532 to 0.512588 and corresponds to the geochemical signature of the waters, oxyhydroxides precipitated from. Samples of iron hydroxides from Quaternary and recent continental ore deposits with different Nd and Sr isotope composition were used for the laboratory reduction of Fe 3+ up to emergence of magnetite ( T ~ 1000°C). 143 Nd/ 144 Nd and 87 Sr/ 86 Sr ratios in the newly formed mineral phases show insignificant discrepancy with parent iron ore. The persistency of Sm–Nd and Rb–Sr isotope systems in the process of bog iron ore experimental melting permits it’s applying to paleoenvironment reconstructions and archaeometry.

Purpose – This paper aims to develop an electrochemical dechlorination method for large objects in a short time, which were for a long time in the sea. Traditionally, in conservation, chlorides are extracted from marine iron artifacts using complete immersion of those objects in alkaline solutions with or without electrolysis. However, these techniques are time-consuming and very costly, especially when applied to large marine artifacts such as cannons and anchors. Design/methodology/approach – An appropriate sponge was chosen based on resistance to NaOH and the rate of exacted chlorides. Application of electrochemical dechlorination in situ and removal of chloride were measured by the scanning electron microscope (SEM)-EDAX method on the corrosion products and by titration of the electrolysis solution. X-ray diffraction (XRD) method is used for identification of corrosion products before and after application of electrochemical chloride extraction. Findings – The electrochemical chloride extraction (ECE) method is applied against the corrosion of reinforced concrete. From the authors’ research, it is obvious that ECE can successfully extract chlorides from dried large metallic objects exported from the sea. The method of ECE removes the majority of chlorides from the metal during conservation treatment so that the application of organic coating will allow the object to remain stable over a long period. Originality/value – A new methodology was developed for dechlorination of metallic objects exported from the sea in a short time and thus the consumption of chemical reagents was cut down.

The main advantage of neutron diffraction over X-ray diffraction, arises from the fact that the interaction of neutrons with material is relatively weak and not related to the number of electrons, and consequently the penetration depth of neutrons is about 10 2 -10 3 larger than that of laboratory X-ray diffraction. This is particular essential for the non-destructive texture analysis of archaeological objects as no additional surface treatments of the samples (e.g. polishing) are necessary. STRESS-SPEC at MLZ is designed as a state of the art multi-purpose diffractometer for strain and texture analysis. Besides the optimized high neutron flux the available large variability in gauge volume definition systems together with the robotic sample handling option offer high flexibility for bulk or gradient texture measurements. Since 2014, local and bulk textures of iron and gold artefacts collected by Bavarian State Archaeological Collection (Munich, Germany) have been thoroughly investigated at STRESS-SPEC. Results showed that heat treatment of iron artefacts at high temperatures can re-orientate the inner crystallites. In the gold foil artefacts, the texture represented by the measured pole figures shows a high symmetry – the so-called Cube component, which is commonly found in annealed fcc materials. For comparison, laboratory samples were produced by rolling, flat hammering, and pin / round hammering and also measured in order to elucidate possible manufacturing and processing routes. In turned out that both rolling and pin / round hammering followed by a high temperature annealing can produce similar pole figures to those of the gold artefacts foils.

Chloride ion migration and the choice of optimized current density during galvanostatic dechlorination of simulated cast iron artifacts in alkaline solution were studied by means of galvanostatic polarization. The results showed that the more treatment time and the more current density, the more was the extraction ratio of chloride ion and the less was the electrical efficiency. The current density was optimized with respect to the extraction ratio of chloride ion and the electrical efficiency, and the optional current density was presented.

The corrosion and preservation of archaeological iron are affected by many factors, among which the role of chloride ions is particularly important. Chloride ion migration and the choice of optimized potential during potentiostatic dechlorination of simulated cast iron artifacts in alkaline solution were studied by means of potentiostatic polarization. The results showed that the more treatment time and the more negative of the potential, the more was the extraction ratio of chloride ion and the less was the electrical efficiency. The potential was optimized with respect to the extraction ratio of chloride ion and the electrical efficiency, and the optional potential was presented.

Field handheld/portable instrumentations, such as in-situ geochemical analyzers, have the potential to assist efficiently targeted geochemical archaeometry campaigns in detecting and quantifying specific elements. Non-destructive portable energy dispersive x-ray fluorescence and micro-destructive handheld laser-induced breakdown spectroscopy (LIBS) instrumentation were utilized to investigate the elemental composition, internal stratigraphy by depth profiling and microscale compositional mapping of five copper and two iron alloy artefacts collected from various ancient graves in the Minervino Murge area, Apulia, Italy. The primary elements identified by both techniques included Cu, Sn and Pb in copper alloys, and Fe with minor amounts of Cu and Pb in iron alloys. Furthermore, the elements Al, Ca, Si, Mg, Na and K, mostly originated from soil contamination, and the trace elements Sb, Ni and Zn were detected. The satisfactory performance of both techniques was assessed by their capacity to provide reproducible elemental composition data. Finally, the depth profile and mapping achieved by LIBS contributed to understanding the metal processing and history of the objects studied, so confirming both techniques to be robust analytical tools in outdoor archaeology and archaeometry campaigns.