Search results for "métallurgie"
showing 10 items of 44 documents
Classification et chronologie de bas fourneaux de réduction du fer à usage unique au sud-ouest du Niger
2016
In southwestern Niger, near Niamey, several thousand single-use bloomery furnaces have been mapped and identified. The archaeological study of approximately 30 furnaces and their slag reveals the existence of four methods for iron smelting: three types of pit furnace and one slag-tapping type. The slag pit furnaces are clearly differentiated by the form and volume of their pits. All slag-tapping furnaces drain off slag through small openings. The slag is tapped either vertically or laterally. According to radiocarbon dates, the smelting activity developed in the 2 nd century AD and intensified through to the 14 th century. It continued to evolve until the middle of the 20 th century. The lo…
Producing and working with iron
2019
Combining archaeological studies and archaeometric analyses, this synthesis presents the importance of the iron economy in the eastern part of the Paris Basin from the First Iron Age to the early Middle Ages. The first contributions of this research project concern technological changes in the production system of iron objects. The attention paid to the share of recycling in production somewhat modifies the previous discourse in attempts to quantify the types of forged objects (tools, weapons, ornaments, etc). Additionally, the link between the status of the excavated sites (agricultural holding, rural hamlet, fortified site, large settlements) and the type of forging activity that was carr…
Experimental investigation and multi-scale modelling of the behavior of mechanically activated metallic powders : from binary systems to High Entropy…
2021
Generally, metal alloys consist of a main element associated with other elements present in smaller quantities such as iron, nickel, aluminum or copper alloys. The precise composition of an alloy is adjusted according to the required performance: high temperature behavior, corrosion resistance, mechanical properties, durability ... In 2004, a Taiwanese scientist, JW Yeh, had the idea of making an alloy base of several elements, at least 5, whose composition in the alloy varies between 5% and 30% at. Yeh invented the high entropy alloy (HEA). Mixed on a microscopic scale, the metals form a remarkably stable solid solution. The explanation is thermodynamic. An alloy is all the more stable as …
La grotte de l'Eremita au Monte Fenera (Vercelli, Italie) : nouvelles découvertes du Bronze moyen
2014
Située au coeur du massif calcaire du Monte Fenera dans le Piémont italien, la grotte de l'Eremita, appelée également Tana dell'Armittu, fait l'objet d'une intervention archéologique menée par l'Université de Genève (direction M. Besse). Suite à des sondages effectués en 2012 lors desquels furent mises au jour, entre autres, des perles spiralées et une épingle en bronze, une fouille programmée a été organisée dès 2013. Notre contribution présente les données de terrains de l'année 2013. La fouille archéologique s'est déroulée avec les étudiants en archéologie, l'aspect didactique - auquel nous sommes fermement attachés - étant un des objectifs de cette fouille.
The Pratz le Curtillet settlement
2016
Among the earliest habitats of the early Middle Ages studied in Franche-Comté, the Pratz le Curtillet a settlement sets itself apart by its location in the Jura highlands, renowned for its remoteness and inhospitable landscapes. On the Lizon plateau, the scope of the archaeological work explored on the 16 hectares and the quality of the remains still constitute an exceptional complex today. An imposing 16m by 13m stone building flanked by an annex forms the residential part of the estate, while sheltering fodder and livestock, while the second building houses a forge. Domestic and artisanal equipment provide ample documentation on the living conditions of this small community of high status…
Development of high entropy tungsten-based alloys by powder metallurgy processes
2022
Although metallurgy is a very old research domain, many innovations are still being considered, such as the emergence of high-entropy alloys. These alloys, composed of at least three elements, are characterized by a chemical composition without a majority element and most of the time equimolar. Research in this field is very recent since the first studies concerning these alloys are from the early 2000s. The original chemical compositions of these alloys open the way to many possibilities to obtain unusual properties.In conjunction with these developments, powder metallurgy processes are expanding quickly because of the advantages they offer over more traditional techniques (foundry and for…
Consolidation and densification mechanisms of copper powder during Spark plasma sintering (SPS)
2015
Spark plasma sintering is a manufacturing process that leads to dense materials with fine microstructures. SPS combines heating and uniaxial load as well as the Hot Pressing (HP) process but the material is heated using a pulsed current. The phenomena occurring during SPS are not fully understood and are still an open point: -Which densification and consolidation mechanisms are involved during SPS? -Why is sintering by SPS more efficient than sintering by traditional ways such as HP? –Does electrical current modify the sintering mechanisms? The aim of this work is to answer these questions in the case of spherical copper powder (from 10 to 50 µm). Comparisons between SPS and HP were perform…
Une production locale d’épées à poignée métallique dans l’est de la France à la fin de l’âge du Bronze ?
2018
International audience; Une première étude croisée des formes et des techniques de fabrication des épées à poignée métallique de la fin du Bronze final au niveau européen a permis de dégager l’hypothèse d’une possible fabrication indépendante de ce type d’arme dans l’est de la France. Cette proposition repose tout particulièrement sur l’étude de deux groupes typologiques contemporains : le type Mörigen et la variante Hostomice du type Tachlovice. Ce travail vise à illustrer le potentiel des études technologiques sur ces épées qui, en complément de la typologie, permettront d’obtenir de précieux renseignement sur les artisans métallurgistes ou encore sur les centres de production et les rése…
La métallurgie du fer au Pays Basque durant l'Antiquité. Etat des connaissances dans la vallée de Baigorri (Pyrénées-Atlantiques)
2003
A study of the ancient metallurgy of iron was committed in the Basque Country, in the Baigorri valley, a rich sector whose resources were exploited before Antiquity and sometimes until the century XXth. The prospecting and the investigations undertaken revealed the existence of two mining and metallurgical districts. Their chronology is attested between the end of the Iron age and the century IVth p.C. The mines, the coal-scuttles and the métallurgie sites of the two centres of production were identified, while four workshops of reduction were the subject of a particular archaeological study. These results were confronted with the environmental data resulting from the palynological and geoc…
Influence of the metallurgy and the microstructure on the strength of titanium-steel laser welded assemblies
2021
The dissimilar laser welding of titanium alloys with stainless steel is of high interest for different industrial applications. However, the joining of these materials by direct fusion is hardly achievable because of the presence of brittle intermetallic phases in the Ti-Fe system that produce spontaneous cracking of the welds. The scientific aim of this thesis is to identify a reliable criterion that allows identifying the possible conditions allowing obtaining a durable dissimilar titanium/steel joints, in terms of mechanical strength in service conditions. The determination of this criterion is necessary for the comprehension of the relation between the microstructure of the melted zone …