The main purpose of this thesis is to perform an electrical and thermal characterization of additively manufactured components made with refractory metals, particularly tantalum. This research is conducted within the context of the SPES project at the Legnaro National Laboratories (LNL-INFN), where refractory metals are often utilized due to their capability of withstanding extreme working conditions, such as ultra-high temperatures and high vacuum; however, refractory metals are challenging to shape because of their high melting temperature, stiffness, and hardness. Consequently, the geometries that can be achieved are quite simple, often requiring difficult machining operations; to address these challenges, Additive Manufacturing techniques are employed, specifically using Laser Powder Bed Fusion (LPBF). This technique starts with metal powders (either pure or properly mixed to achieve the desired alloy), which are melted and fused together by a high-power laser to create the final piece with a specific shape. The focus of this work is to determine if components produced by additive manufacturing (LPBF) exhibit similar material properties to those manufactured using standard methods, identify any differences, and understand the reasons behind these mismatches. The objective is to obtain values for the material properties related to the thermal and electrical fields, specifically thermal conductivity, emissivity, and electrical resistivity. This will provide a comprehensive overview of the behaviour of these refractory metals, with the data being useful for designing SPES components. Tests are conducted at high temperatures and ultra-high vacuum to closely replicate the conditions of the ion source system in the SPES experiment. The work begins with the electrical characterization of additively manufactured pure tantalum specimens to obtain data on electrical resistivity and emissivity. It then goes on with the thermal characterization of several disks made from pure tantalum, with half produced using standard manufacturing techniques and the other half using LPBF. The purpose of these tests is to obtain emissivity and temperature data, which can then be used to determine the thermal conductivity of tantalum and compare the results between standard and additively manufactured samples. Finally, the collected data is used for Finite Element simulations through ANSYS software, particularly for the FEBIAD ion source system, which is a key component of the SPES experiment.
Lo scopo principale di questa tesi è eseguire una caratterizzazione elettrica e termica di componenti prodotti tramite manifattura additiva con metalli refrattari, in particolare tantalio. Questa ricerca si inserisce nel contesto del progetto SPES presso i Laboratori Nazionali di Legnaro (LNL-INFN), dove i metalli refrattari sono spesso utilizzati per la loro capacità di resistere a condizioni estreme di lavoro, come temperature ultra-elevate e alto vuoto; tuttavia, i metalli refrattari sono difficili da modellare a causa della loro elevata temperatura di fusione, rigidità e durezza. Di conseguenza, le geometrie che si possono ottenere sono piuttosto semplici e spesso richiedono operazioni di lavorazione complesse; per affrontare queste sfide, vengono impiegate tecniche di Manifattura Additiva, in particolare la Fusione a Letto di Polvere Laser (LPBF). Questa tecnica usa polveri metalliche (sia pure che miscelate per ottenere la lega desiderata), che vengono fuse e unite insieme da un laser ad alta potenza per creare il pezzo finale con una forma specifica. L'obiettivo di questo lavoro è determinare se i componenti prodotti mediante manifattura additiva (LPBF) presentano proprietà dei materiali simili a quelli fabbricati con metodi standard, identificare eventuali differenze e comprendere le ragioni di tali discrepanze. L'obiettivo è ottenere valori per le proprietà termo-elettriche dei materiali, in particolare la conducibilità termica, l'emissività e la resistività elettrica. Questo fornirà una panoramica completa del comportamento di questi metalli refrattari, con dati utili per la progettazione dei componenti SPES. I test vengono condotti ad alte temperature e in ultra-alto vuoto per replicare da vicino le condizioni del sistema della sorgente ionica nell'esperimento SPES. Il lavoro parte dalla caratterizzazione elettrica di campioni di tantalio puro prodotti mediante manifattura additiva per ottenere dati su resistività elettrica ed emissività. Si prosegue poi con la caratterizzazione termica di diversi dischi realizzati in tantalio puro, metà prodotti utilizzando tecniche di produzione standard e l'altra metà utilizzando LPBF. Lo scopo di questi test è ottenere dati di emissività e temperatura, che possono poi essere utilizzati per determinare la conducibilità termica del tantalio e confrontare i risultati tra campioni prodotti con metodi standard e quelli prodotti con manifattura additiva. Infine, i dati raccolti vengono utilizzati per simulazioni agli Elementi Finiti attraverso il software ANSYS, in particolare per il sistema della sorgente ionica FEBIAD, che è un componente chiave dell'esperimento SPES.
Electrical and thermal characterization of refractory metals manufactured by Laser Powder Bed Fusion
VOLTAN, GIACOMO
2023/2024
Abstract
The main purpose of this thesis is to perform an electrical and thermal characterization of additively manufactured components made with refractory metals, particularly tantalum. This research is conducted within the context of the SPES project at the Legnaro National Laboratories (LNL-INFN), where refractory metals are often utilized due to their capability of withstanding extreme working conditions, such as ultra-high temperatures and high vacuum; however, refractory metals are challenging to shape because of their high melting temperature, stiffness, and hardness. Consequently, the geometries that can be achieved are quite simple, often requiring difficult machining operations; to address these challenges, Additive Manufacturing techniques are employed, specifically using Laser Powder Bed Fusion (LPBF). This technique starts with metal powders (either pure or properly mixed to achieve the desired alloy), which are melted and fused together by a high-power laser to create the final piece with a specific shape. The focus of this work is to determine if components produced by additive manufacturing (LPBF) exhibit similar material properties to those manufactured using standard methods, identify any differences, and understand the reasons behind these mismatches. The objective is to obtain values for the material properties related to the thermal and electrical fields, specifically thermal conductivity, emissivity, and electrical resistivity. This will provide a comprehensive overview of the behaviour of these refractory metals, with the data being useful for designing SPES components. Tests are conducted at high temperatures and ultra-high vacuum to closely replicate the conditions of the ion source system in the SPES experiment. The work begins with the electrical characterization of additively manufactured pure tantalum specimens to obtain data on electrical resistivity and emissivity. It then goes on with the thermal characterization of several disks made from pure tantalum, with half produced using standard manufacturing techniques and the other half using LPBF. The purpose of these tests is to obtain emissivity and temperature data, which can then be used to determine the thermal conductivity of tantalum and compare the results between standard and additively manufactured samples. Finally, the collected data is used for Finite Element simulations through ANSYS software, particularly for the FEBIAD ion source system, which is a key component of the SPES experiment.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/69331