Laser powder bed fusion additive manufacturing of copper wicking structures: fabrication and capillary characterization

Abstract

Purpose An integral component in heat pipes (HPs) and vapor chambers (VCs) is a porous wicking structure. Traditional methods for manufacturing wicking structures within HPs and VCs involve secondary manufacturing processes and are generally limited to simple geometries. This work aims to leverage the unprecedented level of design freedom of laser powder bed fusion (LPBF) additive manufacturing (AM) to produce integrated wicking structures for HPs and VCs. Design/methodology/approach Copper wicking structures are fabricated through LPBF via partial sintering and via the formation of square, hexagonal and rectangular arrangements of micro-pins and micro-grooves, produced in multiple build directions. Wicks are characterized by conducting capillary performance analysis through the measurement of porosity, permeability and capillary rate-of-rise. Findings Copper wicking structures were successfully fabricated with capillary performance, K/reff, ranging from 0.186–1.74 µm. The rectangular-arrangement micro-pin wick presented the highest performance. Originality/value This work represents the first published report on LPBF AM of copper wicking structures for HPs/VCs applications and represents foundational knowledge for fabricating complete assemblies of copper VCs and HPs through LPBF AM.

Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder

“…The flowability and the apparent density of the powders were measured by the Hall flow apparatus. The measured flowrate was 1.32 s/50 g, and the apparent density of the powder was 4.25 g/cm 3 . Figure 1c-f shows the point energy spectrum of powders, and it can be seen that the oxygen content of the powder gradually decreases from the outside shell to the inner core, and the thickness of the oxide layer is less than 1 µm.…”

“…Selective laser melting (SLM), as one of the most promising additive manufacturing (AM) technologies based on powder bed fusion technology that produces metallic components with high relative density layer by layer using the laser as the input heat resource, brings tremendous opportunities for fabricating metallic components, especially those with complex structures [1][2][3]. Compared with traditional casting technology, SLM technology is highly precise and controllable, and can theoretically form arbitrarily shaped parts, allowing more complex and freer structures to be formed directly.…”

Process Parameter Optimization in Metal Laser-Based Powder Bed Fusion Using Image Processing and Statistical Analyses

“…Additive processes have the ability to produce lightweight materials with a complicated design, as well as to reduce the tooling cost, which gives them an edge over conventional manufacturing processes, such as machining in aerospace and medical industries [1,2]. The laser powder bed fusion process has been the subject of extensive research lately [3][4][5][6]. Melt pool physics is one of the most crucial and complicated phenomena during the process.…”

Manufacturing of Tool Steels by PBF-EB

“…Therefore PBF-EB is more preferable for the melting of materials like pure copper or aluminum. Their high thermal conductivity and the reflection of the laser can cause process instabilities and require special lasers in PBF-LB [1]. Further challenges arise upon high residual stresses in the final parts due to fast cooling rates and thermal gradients for both technologies.…”