Fused filament fabrication of ceramic and metallic components for electric propulsion

This thesis investigates the application of Fused Filament Fabrication (FFF) for the production of advanced ceramic and metallic components targeted at electric propulsion (EP) systems, with particular focus on Hall thrusters. The work encompasses both process development and functional design, addressing the full additive manufacturing workflow from feedstock characterization to mechanical testing and system integration. Following an introductory overview of additive manufacturing technologies and their relevance to space applications, the thesis presents a detailed review of Hall thruster physics and typical material requirements, highlighting the challenges and opportunities associated with the use of FFF in this context. The core of the experimental work focuses on two material systems: alumina and 316L stainless steel. For alumina, a complete FFF workflow is developed and optimized, achieving sintered components with relative densities up to 99.9% and flexural strengths up to approximately 430 MPa. These results demonstrate that FFF alumina components can meet the mechanical requirements for functional integration in Hall thrusters. In this work, they were successfully applied to several hollow cathodes, a thermionic emission measurement setup, and a prototype discharge channel for a low-power Hall thruster. For 316L stainless steel, three commercial filaments with different formulations are systematically compared. The study investigates how feedstock characteristics influence shrinkage behavior, densification, and mechanical performance. Optimized processing parameters enable the fabrication of steel parts with relative densities up to 93.9% and ultimate tensile strengths up to 482 MPa, approaching the state of the art for metal FFF. As a demonstrator, a functional stainless steel anode with integrated swirl injection is designed and fabricated for a low-power Hall thruster with anode layer. In addition, the thesis explores an original strategy for joining ceramic and metallic components via shrink-fit interlocking, leveraging shrinkage during sintering to produce robust mechanical assemblies without the need for adhesive or metallurgical bonding. This method is experimentally demonstrated on alumina steel assemblies, with a preliminary evaluation of interfacial quality, sealing behavior, and mechanical performance. Across these investigations, the thesis highlights the strengths and current limitations of FFF for EP applications, providing quantitative benchmarks and practical design guidelines. The results demonstrate that FFF is a viable and versatile approach for the rapid prototyping and functional integration of complex EP components, opening new avenues for low-cost development and design innovation in the field.