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Papers by justine vernet

Archaeometallurgy in Europe 2019, Jun 19, 2019

Copper alloys and casting practices are of major importance in both fields of archaeometry and ma... more Copper alloys and casting practices are of major importance in both fields of archaeometry and material sciences. Universally recognized as key technologies in humankind history, they have known a continuous use through times and still are intensively applied in our modern industry.

Coatings, 2021

One of the most important factors determining a significant reduction in optical devices’ efficie... more One of the most important factors determining a significant reduction in optical devices’ efficiency is the accumulation of soiling substances such as dust, which, especially in solar power plants, implies higher costs and materials ageing. The use of superhydrophobic (SH) coatings, water contact angle (CA) greater than 150°, represents a suitable solution to improve the self-cleaning action while at the same time providing high transmittance for energy conversion. A mixed organic–inorganic SH coating with surface roughness below 100 nm was prepared by an easily scalable spray method and employed, allowing us to modulate the covered area and transparency. The coating has been also investigated while simulating pollution agents like acid rain, harsh environments, and the impact of continuous water droplets and dust particles with different physicochemical properties. The spray coating method allows us to obtain a modulated SH and self-cleaning surface showing CA > 170°, high trans...

Archaeological and Anthropological Sciences, 2020

The Valaisan-type armband (a specific type of bracelet) is a typical metallurgical production fro... more The Valaisan-type armband (a specific type of bracelet) is a typical metallurgical production from the western area of Switzerland belonging to the classic phase of the Aare-Rhone group (BzA2a, ca. 2000–1800 BC). This investigation aims to (i) characterize the metal composition, (ii) reconstruct the thermomechanical treatments applied during the manufacturing process, and (iii) gather information on the possible exploitation of the local ores coupling metallography and chemical analysis. The results show that each armband is manufactured from a hammered sheet of copper-based alloy, containing either tin (up to 3.0 wt.%) or a combination of antimony, nickel, and silver. In several cases, it is assumed that minor elements are already part of the original ore, suggesting a conscious selection of copper veins. In other armbands, a direct addition of cassiterite (SnO2) to the copper matrix is hypothesized based on the material composition and features of the inclusions. Microstructural f...

Journal of Archaeological Science, 2019

The application of lead isotope-based provenance analysis in Southeast Asia over the last decade ... more The application of lead isotope-based provenance analysis in Southeast Asia over the last decade has strongly suggested a central role was played by the Lao PDR in regional copper production exchange networks for approximately 1500 years. The Vilabouly Complex, in central Lao's Savannakhet Province, has revealed major copper mining and smelting sites dated to the regional Iron Age (c. 400 BC-AD 500) and possibly Bronze Age (c. 1000-400 BC). Metallurgical practices at the Vilabouly Complex, and indeed for all of the Lao PDR, are unknown, and the propose of this paper is to provide a comprehensive analytical study of the Vilabouly Complex metal assemblage, including 60 copper-base artefacts of multiple typologies. Cut samples of these were subjected to morpho-stylistic, metallographic (OM), elemental (XRF, SEM-EDS) and lead isotope analyses (MC-ICP-MS) in order to reconstruct the range of forms, metalworking materials, techniques (alloying, casting and post-casting treatments) used at the Vilabouly Complex. The results revealed an assemblage composed of copper, bronze and leaded bronze alloys, with a majority consistent with the lead isotopic signature for the Vilabouly Complex copper. The consistent geochemical and technological signature of the majority of artefacts strongly corroborates the extensive onsite production evidence, and fits with the burgeoning regional copper-base metals database for copper metal demand being sated in large part by Lao PDR supply.

Journal of Archaeological Science: Reports, 2019

Bronze artifacts from Early Bronze Age in Europe often contain white inclusions in the metallic m... more Bronze artifacts from Early Bronze Age in Europe often contain white inclusions in the metallic matrix, that are identified as tin oxides (SnO 2 or Cassiterite). These inclusions are interpreted as un-smelted residues coming from the copper ore and are generally mixed with more complex oxidized inclusions, which contain sulfur, antimony, arsenic, silver, nickel and cobalt. The nature, shape and distribution of these partially smelted tin inclusions give information on the alloying process. Depending on the technological context and the geographical areas, the presence of such inclusions might indicate that the material has been produced by selecting and supplementing of raw materials containing SnO 2 (e.g. co-smelting). In order to understand the role of tin oxide inclusions in the production of bronzes and possible recycling procedures, a crosscutting investigation has been carried out, based on experimental researches. The results show that tin oxides do not completely reduce after four re-melting cycles (recycling) and such a fact is deeply related to the oxygen availability and the dwell time that influences the kinetics of the reaction.

Archaeometallurgy in Europe 2019, Jun 19, 2019

Copper alloys and casting practices are of major importance in both fields of archaeometry and ma... more Copper alloys and casting practices are of major importance in both fields of archaeometry and material sciences. Universally recognized as key technologies in humankind history, they have known a continuous use through times and still are intensively applied in our modern industry.

Coatings, 2021

One of the most important factors determining a significant reduction in optical devices’ efficie... more One of the most important factors determining a significant reduction in optical devices’ efficiency is the accumulation of soiling substances such as dust, which, especially in solar power plants, implies higher costs and materials ageing. The use of superhydrophobic (SH) coatings, water contact angle (CA) greater than 150°, represents a suitable solution to improve the self-cleaning action while at the same time providing high transmittance for energy conversion. A mixed organic–inorganic SH coating with surface roughness below 100 nm was prepared by an easily scalable spray method and employed, allowing us to modulate the covered area and transparency. The coating has been also investigated while simulating pollution agents like acid rain, harsh environments, and the impact of continuous water droplets and dust particles with different physicochemical properties. The spray coating method allows us to obtain a modulated SH and self-cleaning surface showing CA > 170°, high trans...

Archaeological and Anthropological Sciences, 2020

The Valaisan-type armband (a specific type of bracelet) is a typical metallurgical production fro... more The Valaisan-type armband (a specific type of bracelet) is a typical metallurgical production from the western area of Switzerland belonging to the classic phase of the Aare-Rhone group (BzA2a, ca. 2000–1800 BC). This investigation aims to (i) characterize the metal composition, (ii) reconstruct the thermomechanical treatments applied during the manufacturing process, and (iii) gather information on the possible exploitation of the local ores coupling metallography and chemical analysis. The results show that each armband is manufactured from a hammered sheet of copper-based alloy, containing either tin (up to 3.0 wt.%) or a combination of antimony, nickel, and silver. In several cases, it is assumed that minor elements are already part of the original ore, suggesting a conscious selection of copper veins. In other armbands, a direct addition of cassiterite (SnO2) to the copper matrix is hypothesized based on the material composition and features of the inclusions. Microstructural f...

Journal of Archaeological Science, 2019

The application of lead isotope-based provenance analysis in Southeast Asia over the last decade ... more The application of lead isotope-based provenance analysis in Southeast Asia over the last decade has strongly suggested a central role was played by the Lao PDR in regional copper production exchange networks for approximately 1500 years. The Vilabouly Complex, in central Lao's Savannakhet Province, has revealed major copper mining and smelting sites dated to the regional Iron Age (c. 400 BC-AD 500) and possibly Bronze Age (c. 1000-400 BC). Metallurgical practices at the Vilabouly Complex, and indeed for all of the Lao PDR, are unknown, and the propose of this paper is to provide a comprehensive analytical study of the Vilabouly Complex metal assemblage, including 60 copper-base artefacts of multiple typologies. Cut samples of these were subjected to morpho-stylistic, metallographic (OM), elemental (XRF, SEM-EDS) and lead isotope analyses (MC-ICP-MS) in order to reconstruct the range of forms, metalworking materials, techniques (alloying, casting and post-casting treatments) used at the Vilabouly Complex. The results revealed an assemblage composed of copper, bronze and leaded bronze alloys, with a majority consistent with the lead isotopic signature for the Vilabouly Complex copper. The consistent geochemical and technological signature of the majority of artefacts strongly corroborates the extensive onsite production evidence, and fits with the burgeoning regional copper-base metals database for copper metal demand being sated in large part by Lao PDR supply.

Journal of Archaeological Science: Reports, 2019

Bronze artifacts from Early Bronze Age in Europe often contain white inclusions in the metallic m... more Bronze artifacts from Early Bronze Age in Europe often contain white inclusions in the metallic matrix, that are identified as tin oxides (SnO 2 or Cassiterite). These inclusions are interpreted as un-smelted residues coming from the copper ore and are generally mixed with more complex oxidized inclusions, which contain sulfur, antimony, arsenic, silver, nickel and cobalt. The nature, shape and distribution of these partially smelted tin inclusions give information on the alloying process. Depending on the technological context and the geographical areas, the presence of such inclusions might indicate that the material has been produced by selecting and supplementing of raw materials containing SnO 2 (e.g. co-smelting). In order to understand the role of tin oxide inclusions in the production of bronzes and possible recycling procedures, a crosscutting investigation has been carried out, based on experimental researches. The results show that tin oxides do not completely reduce after four re-melting cycles (recycling) and such a fact is deeply related to the oxygen availability and the dwell time that influences the kinetics of the reaction.