Thermal conductivity of metal powders for powder bed additive manufacturing

Wei, Lien Chin; Ehrlich, Lili E.; Powell‐Palm, Matthew J.; Montgomery, Colt; Beuth, Jack; Malen, Jonathan A.

doi:10.1016/j.addma.2018.02.002

Cited by 96 publications

(57 citation statements)

References 56 publications

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“…The measured thermal conductivities in this study are close to the value reported in Ref. 35 for Ti-6Al-4V powder at 1 bar. The interstitial gas content of the powder is shown in Fig.…”

Section: Powder Characteristicssupporting

confidence: 90%

Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Carrion

Soltani-Tehrani

Phan

et al. 2018

JOM

115

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Additive manufacturing technology has enabled industries to generate functional parts with an increased level of complexity via layer-by-layer fabrication. In laser-powder bed fusion (L-PBF), powder is often recycled due to its high cost. However, there is no comprehensive study on how powder recycling affects its rheological properties, as well as the mechanical and fatigue behavior of the manufactured part. This study compares powder characteristics and mechanical performance of as-built and machined specimens fabricated from new and heavily used Ti-6Al-4V powder. Powder characteristics include particle size distribution and morphology, flowability, apparent density, compressibility, thermal conductivity, oxygen concentration, and more. Results indicate that particle size distribution becomes narrower and flowability increases with recycling. Not a significant effect of recycling was observed on the monotonic tensile and fatigue behavior of specimens in the asbuilt surface condition. However, machined specimens fabricated from used powder demonstrated longer fatigue lives in the high cycle regime.

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“…The measured thermal conductivities in this study are close to the value reported in Ref. 35 for Ti-6Al-4V powder at 1 bar. The interstitial gas content of the powder is shown in Fig.…”

Section: Powder Characteristicssupporting

confidence: 90%

Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Carrion

Soltani-Tehrani

Phan

et al. 2018

JOM

115

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“…It is important to distinguish these observations of thermal transport within a crystalline MOF from prior, seemingly contradictory, observations of MOF powders 29 , which show an increase in thermal conductivity upon infiltration with gas. Powder thermal resistances are typically dominated by contact between particles, so that the introduction of a gas helps heat to transfer from one particle to another, exemplified by those systems' pressure-dependent thermal conductivities 48 . Also distinct from MOFs are porous amorphous materials, such as aerogels, which show an increased thermal conductivity with gas pressure 49 .…”

Section: Discussionmentioning

confidence: 99%

Observation of reduced thermal conductivity in a metal-organic framework due to the presence of adsorbates

et al. 2020

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Whether the presence of adsorbates increases or decreases thermal conductivity in metalorganic frameworks (MOFs) has been an open question. Here we report observations of thermal transport in the metal-organic framework HKUST-1 in the presence of various liquid adsorbates: water, methanol, and ethanol. Experimental thermoreflectance measurements were performed on single crystals and thin films, and theoretical predictions were made using molecular dynamics simulations. We find that the thermal conductivity of HKUST-1 decreases by 40-80% depending on the adsorbate, a result that cannot be explained by effective medium approximations. Our findings demonstrate that adsorbates introduce additional phonon scattering in HKUST-1, which particularly shortens the lifetimes of lowfrequency phonon modes. As a result, the system thermal conductivity is lowered to a greater extent than the increase expected by the creation of additional heat transfer channels. Finally, we show that thermal diffusivity is even more greatly reduced than thermal conductivity by adsorption.

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“…Thermal conductivity of PVC aerogels is measured using the hot‐wire method . The hot‐wire method is a standard technique for measuring a wide range of materials . In this method, an electrically resistive metal wire is embedded in the sample, serving as both a line heat source and a temperature sensor, as depicted schematically in Figure a .…”

Section: Properties Of Pvc Aerogels Prepared With Different Porositiesmentioning

confidence: 99%

Ultralight and Flexible Monolithic Polymer Aerogel with Extraordinary Thermal Insulation by A Facile Ambient Process

Qin

Cui

et al. 2019

Adv Materials Inter

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COMMUNICATION (1 of 7)properties. However, most synthesis methods usually involve chemical reactions in gel preparation and are limited to specific materials. In addition, the manufacturing cost introduced by delicate processes such as supercritical drying in preparing high-quality aerogels requires high pressure equipment and consumes large amount of liquid carbon dioxide can pose challenge for large scale deployment.Here, we develop a facile approach to prepare monolithic polymer aerogel based on poly(vinyl chloride) (PVC) via physical processes at ambient environment. Instead of making porous network via crosslink between different molecular chains or covalent bonding between diffe rent nanoparticles, [8,17] the porous network is formed by polymer chains entanglement between different precipitated polymer clusters. Taking advantage of the flexibility of polymer, the porous network remains robust while drying at ambient environment and shows a very low thermal conductivity approaching the air conductivity. Combing with the porosity and pressure dependent thermal conductivity, the thermal transport mechanism in PVC aerogel is carefully analyzed. Furthermore, superhydrophobicity is observed in these synthesized high porosity PVC aerogels.We developed an ambient synthesis process of PVC aerogel mainly consisting of three steps: gelation, solvent exchange, and drying (Figure 1a). First, the reaction sources, i.e., PVC powder (389 293, Sigma-Aldrich, USA) is mixed with dimethylformamide (DMF) (DX1727, EMD Millipore, Germany) with ratio from 0.2 g/10 mL to 1 g/10 mL at temperature of 60 °C. The porosity of aerogel is controlled by tuning the concentrations of PVC solutions. Second, the solution is sonicated for an hour and exposed to air for 12 h, from which the water vapor is absorbed into DMF/PVC solution. Consequently, the solubility of PVC decreases gradually resulting in the precipitation of polymer particles. Finally, a white and jelly-liked PVC solid was formed. To remove the liquid from the PVC gel while avoiding shrinkage of the porous structure, the solvent is exchanged with ethanol, which has a small surface tension. The solvent exchange process includes five steps each with a time interval of 6 h to gradually increase the volume percentage of ethanol in the solvent from 0%, 25%, 50%, 75%, 87.5% to 93.8%.High performance thermal insulation materials are desired for a wide range of applications in space, buildings, energy, and environments. Here, a facile ambient processing approach is reported to synthesize a highly insulating and flexible monolithic poly(vinyl chloride) aerogel. The thermal conductivity is measured respectively as 28 mW (m K) −1 at atmosphere approaching the air conductivity and 7.7 mW (m K) −1 under mild evacuation condition. Thermal modeling is performed to understand the thermal conductivity contributions from different heat transport pathways in air and solid. The analysis based on the Knudsen effect and scattering mean free paths shows that the thermal insulation performance can be f...

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Thermal conductivity of metal powders for powder bed additive manufacturing

Cited by 96 publications

References 56 publications

Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Observation of reduced thermal conductivity in a metal-organic framework due to the presence of adsorbates

Ultralight and Flexible Monolithic Polymer Aerogel with Extraordinary Thermal Insulation by A Facile Ambient Process

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