Processing of complex near-net-shaped tungsten parts by PIM

Hoffmann, J.; Klein, Alice; Gunn, J.; Rieth, M.; Weingaertner, Tobias

doi:10.1016/j.nme.2018.05.023

Cited by 12 publications

(5 citation statements)

References 6 publications

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“…Due to its high hardness and big brittleness, tungsten is very difficult to be machined into components. Traditionally, tungsten is produced by powder metallurgy, spark plasma sintering and powder injection molding [9][10][11]. However, these methods share a common shortcoming that they fail to fabricate complex parts due to the limitation of processing conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of laser scanning strategies on selective laser melting of pure tungsten

Guo

Zhang

et al. 2020

Int. J. Extrem. Manuf.

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Three types of scanning strategies, including the chessboard scanning strategy, the zigzag scanning strategy and the remelting scanning strategy, were conducted to study the effects of scanning strategies on surface morphology, microstructure, mechanical properties and the grain orientation of selective laser melted pure tungsten. The results showed that the pores and cracks were main defects in SLM-processed tungsten parts. The pores could be eliminated using the remelting scanning strategy. However, the cracks seemed to be inevitable regardless of the applied scanning strategies. The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction. A compressive strength of 923 MPa with an elongation of 7.7% was obtained when the zigzag scanning strategy was applied, which was the highest among the three scanning strategies. By changing the scanning strategies, the texture of SLM-processed tungsten in the direction of processing could be changed.

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Section: Introductionmentioning

confidence: 99%

Effects of laser scanning strategies on selective laser melting of pure tungsten

Guo

Zhang

et al. 2020

Int. J. Extrem. Manuf.

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“…As in previous work—FFF and micro injection molding [ 23 , 36 ]—a submicron sized alumina (Al 2 O 3 , TM-DAR, Taimai Chemicals, Tokyo, Japan) was selected as ceramic because of its huge sinter activity enabling density values better than 99% at moderate sinter temperatures (1400 °C) [ 37 ]. The measured average particle size d 50 is around 0.1 µm, the specific surface value, measured via the BET (Brunauer-Emmett-Teller) method, is 11.8 m²/g [ 23 ].…”

Section: Methodsmentioning

confidence: 99%

“…As in previous work-FFF and micro injection molding [23,36]-a submicron sized alumina (Al 2 O 3 , TM-DAR, Taimai Chemicals, Tokyo, Japan) was selected as ceramic because of its huge sinter activity enabling density values better than 99% at moderate sinter temperatures (1400 • C) [37].…”

Section: Materials Selectionmentioning

confidence: 99%

New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts

Nötzel

Hanemann

2020

Materials

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Only a few 3D-printing techniques are able to process ceramic materials and exploit successfully the capabilities of additive manufacturing of sintered ceramic parts. In this work, a new two component binder system, consisting of polyethyleneglycol and polyvinylbutyral, as well stearic acid as surfactant, was filled with submicron sized alumina up to 55 vol.% and used in fused filament fabrication (FFF) for the first time. The whole process chain, as established in powder injection molding of ceramic parts, starting with material selection, compounding, measurement of shear rate and temperature dependent flow behavior, filament fabrication, as well as FFF printing. A combination of solvent pre-debinding with thermal debinding and sintering at a reduced maximum temperature due to the submicron sized alumina and the related enhanced sinter activity, enabled the realization of alumina parts with complex shape and sinter densities around 98 % Th. Finally the overall shrinkage of the printed parts were compared with similar ones obtained by micro ceramic injection molding.

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“…A spectral window of 360 nm to 420 nm was used to observe simultaneously deuterium as the main plasma constituent via D δ and the expected intrinsic and extrinsic impurities W (as WI at 400.8 nm) , O 2 ( OII, 397.3 nm) , and N 2 (NII, 399.5 nm). Plasma density, electron temperature and ion ux in the upper divertor region were measured with a set of embedded Langmuir probes [10]. In order to improve the reconstruction of plasma proles at the target and the exact strike point position, a X-point height sweep was performed in most discharges.…”

Section: Discharge Design and Experimental Setupmentioning

confidence: 99%

Long pulse D₂ and N₂ seeded discharges on the upper actively cooled tungsten divertor of WEST

et al. 2020

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A series of L-mode discharges in upper single null conguration with more than 30 s duration were performed in the WEST tokamak with the strike line on actively cooled W-coated divertor components. This series of discharges accumulated 20 min of plasma and a strike point uence of ≈ 2 × 10 25 m −2 in 2 days of operation in attached conditions. The discharges showed good density control, no tungsten accumulation and an overall very benign thermal behaviour of the upper divertor. A subset of the discharges were seeded with nitrogen either in the divertor or midplane region to study plasma-wall interaction and associated ammonia formation in this weakly pumped scenario with all tungsten plasma facing components. While ammonia signals remained too weak for useful analysis, a strong dependence of nitrogen plasma penetration eciency and residence time regarding the injection location was found. This hints towards a currently underestimated, plasma near nitrogen reservoir in these tokamak discharges in divertor conguration.

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Processing of complex near-net-shaped tungsten parts by PIM

Cited by 12 publications

References 6 publications

Effects of laser scanning strategies on selective laser melting of pure tungsten

Effects of laser scanning strategies on selective laser melting of pure tungsten

New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts

Long pulse D₂ and N₂ seeded discharges on the upper actively cooled tungsten divertor of WEST

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Processing of complex near-net-shaped tungsten parts by PIM

Cited by 12 publications

References 6 publications

Effects of laser scanning strategies on selective laser melting of pure tungsten

Effects of laser scanning strategies on selective laser melting of pure tungsten

New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts

Long pulse D2 and N2 seeded discharges on the upper actively cooled tungsten divertor of WEST

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Product

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Long pulse D₂ and N₂ seeded discharges on the upper actively cooled tungsten divertor of WEST