Microstructural Features in Corroded Celtic Iron Age Sword Blades

Archaeological artefacts made from iron and steel are often of critical importance for archaeometallurgical studies, which aim to understand the process of manufacturing, as the nearly complete alloy mineralization does not allow for any type of metallographic interpretation. In this study, three Iron Age sword blades dated from the second century BC (LaTe`ne B2/D1) found in the archaeological site of Tintignac (Commune de Naves, Corre`ze, France), were investigated. A multianalytical approach was employed to acquire a complete range of data from the partially or totally corroded objects. Analyses were carried out with the use of light optical microscopy, micro Raman spectroscopy, and scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy (EDXS). Remnants of metallographic features\u2014ghost microstructure\u2014in the corrosion layers of the blades were observed, allowing for a partial reconstruction of the manufacturing process

ICP-AES and MicroRaman corrosion behaviour investigation on Zn4Sb3 and Al, Ag doped phases in sodium chloride solution

The high thermoelectric performance of the b-phase Zn4Sb3 has drawn much attention for its application in the intermediate temperature range. In this work we explore the corrosion behaviour properties of pure Zn4Sb3 compound and after partial substitution of Zn with Al and Ag. In particular, Zn4Sb3, (Zn1xAlx)4Sb3 and (Zn1xAgx)4Sb3 (x = 0.01) compounds were synthesized using a muffle furnace and characterized in terms of crystal structure, morphology and phases composition (SEM-EDXS, XRD). All samples were placed in 0.1 M NaCl aerated solution at room temperature for 48 days. A study of the amount of cations released in solution was carried out using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) analysis. Analytical data reveal a higher value of zinc amount for doped samples. The microRaman spectroscopy analysis carried out on surface corrosion products revealed the presence of anhydrous and hydrate zinc hydroxy chlorides. No worsening on corrosion behaviour of Zn4Sb3 intermetallic compounds was observed after Al or Ag doping

Micro-Raman spectroscopy for the characterization of artistic patinas produced on copper-based alloys

In order to contribute to the improvement of restoration and conservation sciences of metallic artefacts belonging to Cultural Heritage, a wide research has been started on the study of artificial (artistic) and natural (corrosion or alteration) patinas of copper-based alloys. Micro-Raman spectroscopy (mRS) coupled with scanning electron microscopy (SEM) equipped with energy Dispersive X-Ray Spectroscopy (EDXS) were applied for the characterization of a number of patinas made on metallic substrate reproducing the typical copper-based alloys used for statuary. A non alloyed copper sheet has been also used to simulate the architectural cover typically used after a specific cold spray coating. To reach these goals, a number of patinas were experimentally produced in our laboratory using the torch technique and reactive solutions based on water as a solvent containing, respectively, copper nitrate, iron nitrate and potassium sulfide (\u2018liver of sulfur\u2019). The only exception is a sample reproducing the architectural cover of a recent building nearly completely covered with copper sheets coated with copper salts. All the produced patinas were aged in a salt spray chamber and then studied with mRS, SEM and EDXS in order to understand their evolution between the two known terms and therefore the reactions involved in all patinas. mRS allowedus todetect asmain constituents of the \u2018artistic\u2019 patinas, before and after ageing: copper oxides (Cuprite and Tenorite), copper nitrates (Rouaite and Gerhardtite), copper chlorides (Botallackite, Atacamite and Paratacamite), a copper sulfate (Posnjakite), iron oxides (Magnetite and Hematite) and an iron hydroxide (Limonite)