Materials development for new high heat-flux component mock-ups for DEMO

Coenen, J. W.; Mao, Y.; Sistla, S.; Müller, A. von; Pintsuk, G.; Wirtz, M.; Riesch, J.; Hoeschen, T.; Terra, A.; You, J.-H.; Greuner, H.; Kreter, A.; Broeckmann, C.; Neu, R.; Linsmeier, Ch.

doi:10.1016/j.fusengdes.2019.02.098

Cited by 25 publications

(15 citation statements)

References 57 publications

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“…For both PM W f /W as well as CVD W f /W, upscaling is crucial for further applications; thus, the development of larger scale material samples, mockups, [139] and their tests is an important part of the W f /W development. For the PM W f /W, upscaling is related to the application of FAST on larger scale material samples, and thus relatively straight forward.…”

Section: W Compositesmentioning

confidence: 99%

Fusion Materials Development at Forschungszentrum Jülich

Coenen

2020

Adv Eng Mater

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Material issues pose a significant challenge for the design of future fusion reactors. From a historic point of view, the material mix used for the first wall of a fusion reactor has continually evolved, from original steel vessels to carbon and other low-Z materials such as beryllium to tungsten as the primary candidate for a reactor's first wall armor and divertor material. For materials considered for fusion applications, a highly integrated approach is necessary. Resilience against neutron damage, good power exhaust, and oxidation resistance during accidental air ingress are design relevant issues while deciding on new materials or improving upon baseline materials. Neutron-induced effects, e.g., transmutation adding to embrittlement, retention, and changes to thermomechanical properties, are crucial to material performance. In this contribution, the recent progress (2013-2019) in fusion materials development for current and future fusion devices, at Forschungszentrum Jülich GmbH, with activities focussing on advanced materials and their characterization is given. It is a continuation and extension of the work given by Coenen et al.

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Section: W Compositesmentioning

confidence: 99%

Fusion Materials Development at Forschungszentrum Jülich

Coenen

2020

Adv Eng Mater

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“…In the next step, the coated fibers are embedded in the W matrix. In addition to powder metallurgy utilizing 1.5-2.5 mm short fibers [25][26][27], a possible synthesis route is chemical vapor deposition (CVD) on several cm long fibers or textile pre-forms [28,29]. For this work, CVD was used with tungsten hexafluoride (WF 6 ) and hydrogen (H 2 ) as gaseous precursors.…”

Section: Introductionmentioning

confidence: 99%

Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites

Raumann

Coenen

Riesch

et al. 2021

Metals

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Tungsten (W) has the unique combination of excellent thermal properties, low sputter yield, low hydrogen retention, and acceptable activation. Therefore, W is presently the main candidate for the first wall and armor material for future fusion devices. However, its intrinsic brittleness and its embrittlement during operation bears the risk of a sudden and catastrophic component failure. As a countermeasure, tungsten fiber-reinforced tungsten (Wf/W) composites exhibiting extrinsic toughening are being developed. A possible Wf/W production route is chemical vapor deposition (CVD) by reducing WF6 with H2 on heated W fabrics. The challenge here is that the growing CVD-W can seal gaseous domains leading to strength reducing pores. In previous work, CVD models for Wf/W synthesis were developed with COMSOL Multiphysics and validated experimentally. In the present article, these models were applied to conduct a parameter study to optimize the coating uniformity, the relative density, the WF6 demand, and the process time. A low temperature and a low total pressure increase the process time, but in return lead to very uniform W layers at the micro and macro scales and thus to an optimized relative density of the Wf/W composite. High H2 and low WF6 gas flow rates lead to a slightly shorter process time and an improved coating uniformity as long as WF6 is not depleted, which can be avoided by applying the presented reactor model.

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“…New advanced-options for use as PFCs are being developed (see [14,15,16,17,8], and references therein) focussing on crack resilient composites with low activation, now or low tritium uptake, enhanced lifetime and low erosion. Many advanced materials base their improved properties on the use of a composite approach.…”

Section: Introductionmentioning

confidence: 99%

The use of tungsten yarns in the production for W_f/W

et al. 2020

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Material issues pose a significant challenge for the design of future fusion reactors. Recently progress has been made towards fully dense multi short-fibre powder metallurgical production of tungten-fibre reinforced tungsten (W f /W) as well as optimising the process understanding for the routes using chemical vapor deposition (CVD). For CVD-W f /W weaves and textile preforms are being used to facilitate large scale production. Classically 150 µm tungsten fibres supplied by OSRAM GmbH have been used. In order to facilitate the better use of textile processes less stiff 16 µm filaments are being evaluated. The strength of the 16 µm flament is at 4500 M P a and thus significantly higher than the strength of the 150 µm fibre (∼2500 MPa) (in the as-fabricated state). Better weavability allows a more flexible use of fibre preforms. Two main yarn production routes have been investigated: covered yarns where a set of tungsten filaments is held together by a PVA (Polyvinyl alcohol) cover and braided yarns. In oder to allow a comparison to the previously used single fibres, yarns with ∼ 140 µm effective diameter were produced. Braided yarns with tensile strength of 2500 MPa and 6% strain at fracture and twisted yarns with tensile strength of 4500 MPa and 3% strain at fracture. For both yarns single fibre CVD samples have been produced to investigate the infiltration properties of the yarns and thus their applicability for the CVD route. A dense infiltration is observed for all yarns under investigation.

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Materials development for new high heat-flux component mock-ups for DEMO

Cited by 25 publications

References 57 publications

Fusion Materials Development at Forschungszentrum Jülich

Fusion Materials Development at Forschungszentrum Jülich

Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites

The use of tungsten yarns in the production for W_f/W

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Materials development for new high heat-flux component mock-ups for DEMO

Cited by 25 publications

References 57 publications

Fusion Materials Development at Forschungszentrum Jülich

Fusion Materials Development at Forschungszentrum Jülich

Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites

The use of tungsten yarns in the production for W f /W

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The use of tungsten yarns in the production for W_f/W