Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Technological challenges >> Additive manufacturing, new routes for saving materials
4 proposition(s).

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Study and development of thermoelectric materials by additive manufacturing

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Modélisation et Matériaux pour la Métallurgie

01-10-2021

SL-DRT-21-0536

guilhem.roux@cea.fr

Additive manufacturing, new routes for saving materials (.pdf)

For 15 years, the laboratory L3M has acquiered a big experience in thermoelectricity (TE), mainly in thin films and bulk technologies. Thermoelectricity converts thermal energy into electrical Energy (Seebeck effect), and reciprocally (Peltier effect). For 5 years, L3M has also acquiered a strong experience in additive manufacturing (AM), mainly for metallic materials. The use of AM for TE offers new perspectives, and enables to vreate new complex geometries (leading to an optimization of yield and/or a better integration), with less materials losses, a significant decrease of the integration and interface challenges, a faster manufacturing time, a lower cost and the possibility to manufacture TE devices very quickly compared to other technologies. The main barrier consists in obtaining materials with as good quality as with other technologies (in terms of density and microstructure), which will be possible thanks to a deep development of the process. Two families of TE materials will be studied: Bi2Te3 and MnSi/FeGe. The first one is the reference in the temperature range 300-500 K and the second one in the temperature range 500-700 K. The objective of this PhD study will be to study and optimize materials manufacturing processes obtained by AM (by the Laser Powder Bed Fusion (L-PBF) technology). This study will enable understanding and highlighting specifities of AM mechanisms on TE materials structural properties. This structural study will include measurement of mechanical properties, as well as microscopic analysis. This study will also correlated to experimental measurements of manufactured materials TE properties (Seebeck coefficient, electrical and thermal properties). Up to now, no thermoelectric device has been manufactured by this technology. TE device manufacturing needs to associate two TE materials and assemble together, by optimizing electrical contacts between these two materials. CEA-Liten has deposited a patent about the original manufacture of such device by AM. The realisation and electrical characterization of a first TE prototype will be also developed in he Framework of this study. It will enable highlighting advantages of this technique, such as manufacturing of complex geometries, less materials losses, a shorter manufacturing time, etc.

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Architectured materials for heat exchangers applied to the energy transition

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Modélisation et Matériaux pour la Métallurgie

01-09-2021

SL-DRT-21-0731

guilhem.roux@cea.fr

Additive manufacturing, new routes for saving materials (.pdf)

This project concerns the eco-innovation of multi-scale 3D printed architectured structures for innovative reactor-exchangers. The ambition is to improve the performance in terms of kinetics, stability and selectivity of chemical reactions used in the field of hydrogen production or recovery. The structures developed will be optimized by thermal simulation in order to maximize their efficiency by taking advantage of additive manufacturing geometric possibilities. The targeted applications are the production of synthesis gas by catalytic processes: CO2 methanation [1], Fischer-Tropsch reactions, LOHC technology or even the decomposition of NH3. As part of the thesis, it is proposed that one of these applications be treated as a priority. Scientific challenges considered during this thesis will be the development of reliable thermo-fluidic simulation tools at the scale of elementary cells (Representative Elementary Volume) by coupling thermal simulation for the solid part and lattice Boltzmann method for the fluid part. Using an upscaling strategy, modeling at the representative scale of the useful reactors sections (mesoscopic calculation) as well as full scale reactors will be carried out using finite element method (Comsol). A screening of elementary structures will be carried out beforehand in order to identify the most suitable structures for each application, using a design tool for elementary structures. Final expectations will feed several circular economy action levers to reduce economic (competitiveness with more compact, more selective exchangers) and environmental impacts (low in energy and material): increase the process efficiency, increase catalyst lifetimes and decrease in ecological impact through a comparative environmental impact analysis (LCA). This thesis will be a collaboration between DAM/Le Ripault and DRT /Liten. The first year of the thesis will be conducted at Le Ripault (Tours) and the last two years in Grenoble.

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Multi-functional material for catalytic hydrogenation of CO2 to methanol and dimethyl-ether

Département Thermique Conversion et Hydrogène (LITEN)

Laboratoire réacteurs et procédés

01-09-2021

SL-DRT-21-0750

albin.chaise@cea.fr

Additive manufacturing, new routes for saving materials (.pdf)

Hydrogen production by water electrolysis coupled to catalytic hydrogenation of CO2 into hydrocarbon or oxygenates of high energetic Density (methanol, DME) can contribute to the decarbonation of transportations (sea, air transportation) and provide products for a sustainable chemistry. However, these reactions are limited thermodynamically. The current PhD proposal aims at developing a coupled system of catalytic reaction (CuZnO/Al2O3 and zeolites), de-hydratation by separation and/or adsorption of water (ZSM5 and LTA zeolites) for direct synthesis of methanol and DME form CO2. Non-critical and recyclable material (Cu, Zn, Al) and low environmental footprint processes (supercritical CO2, hydrothermal, micro-waves) or bio-templates. One essential goal will be to obtain 3D oriented zeolites with limited defaults, first on planes surfaces then on 3D structures (ceramics or metal). The intrinsic material performances will first be tested on samples. Then the material will be integrated in a 3D reactor with catalysts at the scale of a few L/min of reactants.

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Numerical simulation for processing powder bed additive manufacturing

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Modélisation et Matériaux pour la Métallurgie

01-09-2021

SL-DRT-21-0752

guilhem.roux@cea.fr

Additive manufacturing, new routes for saving materials (.pdf)

The project concerns the study of powder spreading in the context of powder bed additive manufacturing processes, in particular L-PBF (Laser-, Powder Bed Fusion) and MBJ (Metal Binder Jetting) processes. The ambition is to give CEA a reliable simulation tool making it possible to reproduce what happens during this process key stage, when the real powder bed (intended to be melted or agglomerated depending on the technologies) is spread out. This project will be fed by results from a dedicated instrumented spreading set-up as well as by elementary experiments. The simulation will be based on DEM method (discrete element method, [1]), benefiting from developments acquired by the partners (DES/IRESNE) in powder transitics and from first developments in progress at DRT / LITEN. The particle interaction behavior models will be fed by a wide range of real characterizations under elementary flow conditions. The models will then be initially compared on these elementary tests, then ultimately on real full-scale results obtained on the specific DRT/LITEN spreading set-up. Today, several works are carried out on this subject ([2] [3] [4] [5]), but they take into account idealized, spherical and mainly monodisperse powders. The originality of this work compared to the state of the art is to investigate beyond the behavior of model powders by taking into account real morpho-physico-chemical state of various powders (surface roughness, sphericity, charge electrostatic effect, effect of humidity, effect of oxidation state,?) of powders. In particular, one objective will be to understand the mechanisms powders ageing and their consequence on flowability, a real industrial issue. In addition, this study will show the consequences on the flowability of composite powders developed at CEA ([6] [7]). This thesis will be a collaboration between DES/IRESNE and DRT/LITEN.

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