Search results for "spark plasma sintering"
showing 10 items of 40 documents
Spark Plasma Sintering à partir de poudres mécaniquement activées : compréhension des transitions de phase au cours d'un frittage réactif
2007
International audience; À " basse température " (entre 400 et 600 ◦C), l'oxydation de MoSi2 entraîne sa désintégration en poudre (phénomène de " peste "). De récents travaux ont montré que l'utilisation de MoSi2 dense et nano-organisé permettrait de ralentir ce phénomène de " peste ". Le défi de produire des matériaux denses et nano-organisés peut être relevé par le frittage " flash " réactif sous champ électrique à partir des poudres mécaniquement activées (Mechanically-Activated Spark Plasma Sintering, MASPS). Le contrôle de la composition et de la microstructure du composé intermétallique MoSi2 nécessite de déterminer les paramètres du frittage SPS (température, rampe de montée en tempér…
Synthesis of FeAl Hetero-Nanostructured Bulk Parts via Spark Plasma Sintering of Milled Powder
2006
AbstractSpark plasma sintering (SPS) has been used in order to introduce nanocrystalline grains within fully dense FeAl consolidated parts. Hetero-nanostructured parts, consisting of nano, ultrafine and micrometric grains, have been successfully processed when milled - Y2O3 reinforced - FeAl powder was used. The large temperature differences that are spontaneously generated during the SPS process as well as the use of milled powder account for the formation of such interesting structures. The grain size distribution - that is suggested to be very potent to improve both strength and ductility - could be significantly modified by a proper selection of sintering temperature and holding time.
Oxidation resistance of Ti 3 AlC 2 and Ti 3 Al 0.8 Sn 0.2 C 2 MAX phases: A comparison
2019
Ti3AlC2 and Ti3Al0.8Sn0.2C2 MAX phase powders are densified using Spark Plasma Sintering technique to obtain dense bulk materials. Oxidation tests are then performed over the temperature range 800-1000°C under synthetic air on the two different materials in order to compare their oxidation resistance. It is demonstrated that, in the case of the Ti3Al0.8Sn0.2C2 solid solution, the oxide layers consist in TiO2, Al2O3 and SnO2. The presence of Sn atoms in
Reactive Sintering of molybdenum disilicide by Spark Plasma Sintering from mechanically activated powder mixtures: Processing parameters and properti…
2008
Abstract Dense molybdenum disilicide with a nano-organized microstructure was synthesized by mechanical activation, by producing nanostructured agglomerates of a 1:2 mixture of Mo and Si, followed by the synthesis/consolidation in one step using SPS technology. In order to synthesize a dense molybdenum disilicide with a perfectly controlled microstructure, an investigation of the influence of Spark Plasma Sintering processing parameters (temperature, heating rate, mechanical pressure and holding time) on the chemical composition and the microstructure characteristics has been performed. The present work shows also that the so-obtained materials present better oxidation resistance in compari…
Spark Plasma Sintering of Metallic Glasses
2019
Spark plasma sintering (SPS) of metallic glasses (MG) can be quite different from sintering crystalline metallic alloys. Indeed, MG behave differently with increasing temperature, as they encounter a glass transition and devitrification. Their shaping can thus be compared to what can be performed on thermoplastic polymers. SPS is a promising way to prepare bulk parts from amorphous powders, since it allows very fast heating and cooling rates. It gives an advantage to avoid or limit devitrification of the amorphous phase upon the thermal cycle. However, diffusion mechanisms, which generally control densification, are activated at temperatures that are not compatible with MG structural integr…
Production of dense nanostructured materials using FAPAS and SPS techniques
2011
International audience
Elaboration of metal / ceramic functionally graded materials by SPS for ballistic protection
2016
The objective is to improve ballistic performance of armors. A perfect armor combines ductility to resistto the impact and high hardness to stop projectile’s fragments. However, such an association of properties is inconsistent witha single material. The solution is to perform a functionally graded material (FGM) with a ductile metal at the back side of thesample and a hard ceramic on the top side. Non-conventional technologies like Spark Plasma Sintering allow joining orsintering all types of materials with different and additional properties. Furthermore, with this technique, high heating ratescan be achieved, limiting grain growth and resulting in a fine microstructure. The goal is to st…
Microstructure and mechanical effects of spark plasma sintering in alumina monolithic ceramics
2013
The specific effects of spark plasma sintering (SPS) on the creep behavior, microstructure and mechanical properties of alumina monolithic ceramic were investigated. SPS introduces strains that concentrate at grain boundaries and inhibit crack growth, resulting in an improvement in the flexural strength and fracture toughness. However, creep blocks grain boundary movements and decreases the reliability of the material. These strains can be removed by a post-sintering thermal treatment, which plays an important role in the distribution of dislocations.
Spark Plasma Sintering (SPS)-Assisted Synthesis and Thermoelectric Characterization of Magnéli Phase V6O11
2018
The Magneli phase V6O11 was synthesized in gram amounts from a powder mixture of V6O11/V7O13 and vanadium metal, using the spark plasma sintering (SPS) technique. Its structure was determined with synchrotron X-ray powder diffraction data from a phase-pure sample synthesized by conventional solid-state synthesis. A special feature of Magneli-type oxides is a combination of crystallographic shear and intrinsic disorder that leads to relatively low lattice thermal conductivities. SPS prepared V6O11 has a relatively low thermal conductivity of κ = 2.72 ± 0.06 W (m K)-1 while being a n-type conductor with an electrical conductivity of σ = 0.039 ± 0.005 (μΩ m)-1, a Seebeck coefficient of α = -(3…
Effect of current on the sintering of pre-oxidized copper powders by SPS
2017
Abstract As mentioned in the literature, SPS (Spark Plasma Sintering) technology combines uniaxial charge and pulsed currents to achieve the rapid sintering of powders. Although the utilization of current is often reported, an understanding of its role in the sintering mechanisms is still a subject of controversy. In fact, the oxide layer around metal particles is sometimes considered to be a dielectric gap in which discharges may occur: these discharges can clean the surface of particles and enhance densification. In this paper, an oxide layer was grown on the particle surface of a copper powder, and the growth enabled the study of the role of current on such dielectric layers. The powders…