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195330 https://hdl.handle.net/2286/R.2.N.195330 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2024 2026-08-01T16:05:10 208 pages Doctoral Dissertation Academic theses Text eng Noe, Cameron Scott Bhate, Dhruv Phelan, Patrick Kwon, Beomjin Arizona State University Partial requirement for: Ph.D., Arizona State University, 2024 Field of study: Manufacturing Engineering Additive manufacturing (AM) enables design freedom previously not attainable with traditional manufacturing techniques. By developing a method of integrating heat pipe geometry into printed parts as a monolithic structure, designers can potentially increase thermal performance in a wide variety of components such as radiators. Traditional manufacturing of high temperature radiators, for example, involves heat-pipe-to-fin interfaces which introduce contact resistances and thermal stresses arising from coefficient of thermal expansion (CTE) mismatches. A monolithic additively manufactured heat pipe radiator (HPR) could significantly reduce these detrimental effects to performance.The goal of this research is to develop and design AM heat pipes, characterize their performance, and integrate these heat pipes into a functional device, an AM Monolithic Heat Pipe Radiator (MHPR). These MHPR devices could potentially improve thermal management for applications such as nuclear spacecraft propulsion and hypersonics. This thesis specifically explores AM produced Inconel 718 to produce functional wicking structures. During the study several design approaches for creating heat pipe wicks with AM processes were explored and proposed for the first time in three categories as structured, sintered, and rastered approaches. Several aspects of wick design were studied to understand their influence on fluid wicking performance including porosity, print parameter selection, surface oxidation, print orientation, working fluid interaction, permeability, capillary pressure, pore size, and performance ratio. Manufacturing defect modes for AM wicks were also studied. This thesis identified the rastered wicking strategy, with high hatch spacings and printed in the vertical print orientation, as the design strategy with the highest overall performance for monolithic HPR applications. The sintered wicking strategy was found to perform well when designs had thin wick regions in the horizontal print orientation and was less prone to manufacturing defects. Oxidation of the Inconel wicks greatly improved the wettability of the wick surface when using water as a working fluid but was less influential with ethanol. This thesis uncovers the important role of both surface assisted wetting and geometry assisted transport channels for superior wick performance. Several monolithic HPR prototypes were produced using AM and successfully tested in space-like conditions. Engineering Aerospace Engineering Materials Science Additive Manufacturing Heat pipes Inconel 718 Laser Powder Bed Fusion Monolithic Heat Pipe Radiator wicking Additive Manufacturing of Fluid Wicking Structures in Inconel 718 for use in Monolithic Integrated Heat Pipes Using Laser Powder Bed Fusion (LPBF)