Search results for "Spark plasma sintering"
showing 10 items of 40 documents
Spark Plasma Sintering tool design for preparing alumina-based Functionally Graded Materials
2016
Abstract A way to produce Functionally Graded Materials (FGM) is by means of Spark Plasma Sintering (SPS) and specifically designated tools. These new tools permit a current density modulation and therefore a temperature variation along the z-axis. The key feature relies on a varying die section. FEM modelling has given the suitable range of die dimensions between the top and the bottom to obtain a given temperature gradient (around 300 °C) out of roughly a 15 mm height. Experiments conducted in different configurations (with or without samples) and the measurement of the associated thermal gradient led to improvements of the mould (in particular the introduction of a counter-piston). By th…
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…
Spark plasma sintering of zirconia/nano-nickel composites
2015
Open Access
Spark plasma synthesis from mechanically activated powders: a versatile route for producing dense nanostructured iron aluminides
2004
Abstract The possibility of mechanically activated spark plasma sintering (MASPS) to perform simultaneously within a very short period of time the synthesis and the consolidation of nanophase iron aluminide from mechanically activated powders of Fe and Al in two different ratio (Fe53 at.% and Fe60 at.%) were confirmed in this work.
Bulk FeAl nanostructured materials obtained by spray forming and spark plasma sintering
2007
Abstract This paper examines the efficiency of two consolidation processing techniques high velocity oxy-fuel (HVOF) spray forming and spark plasma sintering (SPS) which allow to obtain bulk dense nanostructured materials. An oxide dispersion strengthened (ODS) Fe–40Al (at.%) based milled powder (with a nanostructure
Improvement of the critical current density of spark plasma sintered MgB2by C60addition
2010
We investigated the influence of fullerene (C60) addition on the superconducting parameters of MgB2 bulk samples obtained by spark plasma sintering (SPS). It was found that 1.5?wt% C60 addition leads to the reduction of the critical temperature by a few K, whereas the magnetically determined critical current density increases by approximately one order of magnitude in an applied magnetic field H = 70?kOe at temperature T = 10?K. This indicates substitution of B by C in C60 added MgB2 processed by SPS, contrary to some data reported in the literature obtained using conventional methods. For our relatively large specimens, the occurrence of macroscale flux jumps was observed over a wide (H, T…
Mechanical, thermal and electrical properties of nanostructured CNTs/SiC composites
2018
International audience; Dense SiC-based nanostructured composites reinforced by well-distributed carbon nanotubes (CNTs) were elaborated for the first time by spark plasma sintering (SPS) without sintering additive. Microstructures of materials containing different amounts of CNTs – up to 8.0 vol% – were correlated with their mechanical, electrical and thermal properties. A continuous decrease of the SiC grain size was observed when the amount of CNT was increased, while the evolution of density showed a different behavior that could be explained by the particular combination of SPS technique with the electrical resistivity evolution of the green bodies. Optimal effect of CNTs addition on h…
Elaboration de matériaux à gradient de propriétés fonctionnelles pour les composants face au plasma des machines de fusion thermonucléaires
2014
The objective of this study was to develop a Functionally Graded Material (FGM) W / Cu to replace the compliance layer (Cu-OFHC) in the plasma facing components of thermonuclear fusion reactor like ITER. The peculiarity of this work is to elaborate these materials without exceeding the melting temperature of copper in order to control its microstructure. The co-sintering is the most attractive solution to achieve this goal.The first phase of this study has been to decrease the sintering temperature of the tungsten to achieve this co-sintering. The elaboration of a Functionally Graded Materials being delicate, thermo-mechanical calculations were performed in order to determine the number and…
Ceramique/metal component elaborated by flash sintering for ballistic protection
2012
This dissertation describes the synthesis of new components for ballistic protection with the assistance of flash sintering. Indeed, the objective is to associate two compounds showing very different sintering temperatures – such as alumina and aluminum, two reference materials for ballistic protection applications.The first synthesis method tested was the elaboration of a bi-material via the sintering of aluminump owder on alumina bulks. This study permitted to observe the formation of the alumina/aluminum bonding by scanning and transmission electron microscopy and to optimize the assembly parameters in order to obtain a bimaterials howing a strong interfacial cohesion. Adapted characteri…
Elaboration de céramiques transparentes Er YAG : synthèse de poudre par co-précipitation et frittage SPS
2013
Yttrium aluminium garnet (YAG, Y3Al5O12) transparent ceramics have attracted much attention since it can replace single crystals as host materials in solid state heat capacity lasers. These polycrystalline ceramics present improved mechanical and spectroscopic properties, as well as a better heat conductivity, lower fabrication costs for larger size materials. Furthermore, it is possible to reach higher doping concentrations as well a uniform distribution. Doping YAG with Erbium (Er:YAG) allows eye-safe emission at 1645nm. Moreover, a low doping rate (0.5%at.) enables upconversion process during laser operation. Conditions for transparency are amongst others, the absence of defects, a high …