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Procédé de projection plasma en mode pulsé associé à une injection jet d'encre synchronisée : mise au point, processus en vol et élaboration de dépôts céramiques

Abstract : In the field of thermal spray coating processes, research has led to the development of nanostructured coatings by suspension plasma spraying (SPS) and precursor solution plasma spraying (SPPS). Liquid injection are promising techniques with the potential to become industrially viable. However, a better control of plasma/material interactions is necessary. Mono-electrode DC torches indeed generate strongly fluctuating plasma that modifies the thermal and dynamic transfers to the injected droplet, resulting in an inhomogeneous treatment of the latter. This directly influences the texture and microstructure of deposits and subsequently their properties. Previous works have shown the origins of these instabilities. As an alternative to instabilities attenuations, a new approach is proposed: the reinforcement and modulation of the instabilities. The adjustment of process parameters has allowed obtaining a pulsed laminar plasma with a modulation of its properties. A low powered home-made modulated DC torch is used and operates with pure nitrogen as plasma forming gas. This device is synchronized with a Drop-On-Demand injection system to reproduce the same conditions of plasma/material interactions for each injected droplet. Solutions and suspensions are injected to make homogeneous coatings with controlled microstructure. The objectives of this work are firstly to characterize and understand plasma / droplet heat and dynamics transfers. Secondly, to highlight the influence of the synchronization and operating parameterson the coatings obtained.
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https://tel.archives-ouvertes.fr/tel-01680002
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Submitted on : Monday, January 15, 2018 - 2:23:54 PM
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Fabrice Mavier. Procédé de projection plasma en mode pulsé associé à une injection jet d'encre synchronisée : mise au point, processus en vol et élaboration de dépôts céramiques. Matériaux. Université de Limoges, 2017. Français. ⟨NNT : 2017LIMO0065⟩. ⟨tel-01680002v2⟩

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