Tungsten coatings for the JET ITER-like wall project

Maier, H.; Neu, R.; Greuner, H.; Hopf, C.; Matthews, G. F.; Piazza, G.; Hirai, T.; Counsell, G.; Courtois, X.; Mitteau, R.; Gauthier, E.; Likonen, J.; Maddaluno, G.; Philipps, V.; Riccardi, B.; Ruset, C.

doi:10.1016/j.jnucmat.2007.01.246

Cited by 40 publications

(34 citation statements)

References 10 publications

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“…An alternative solution consists in coating the parts to protect with a W layer. Much work has been devoted to investigate suitable coating technologies and plasma spray (PS) in vacuum [2,9], physical vapor deposition (PVD) [10,11], and chemical vapor deposition (CVD) [12] have been proposed and tested under high heat flux loading. Yahiro et al [13] investigated air plasma spray (APS) comparing the characteristics of coatings with those obtained through PS made in vacuum.…”

Section: Introductionmentioning

confidence: 99%

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

Montanari

Pakhomova

Pizzoferrato

et al. 2017

Metals

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Tungsten (W) is considered a promising plasma-facing material for protecting the divertor of the ITER (International Thermonuclear Experimental Reactor). The effects on W of transient thermal loads of high energy occurring in a tokamak under operative conditions have been simulated through a single laser pulse delivered by an Nd:YAG laser. Bulk and plasma-sprayed (PS) samples have been submitted to tests and successively examined via SEM (scanning electron microscopy) observations. In both types of materials, the laser pulse induces similar effects: (i) a crater forms in the spot central area; (ii) all around the area, the ejection and the movement of molten metal give rise to a ridge; (iii) in a more external area, the surface shows plates with jagged boundaries and cracks induced by thermal stresses; (iv) the pores present in the original material become preferred ablation sites. However, the affected surface area in PS samples is larger and asymmetric if compared to that of bulk material. Such a difference has been explained by considering how microstructural characteristics influence heat propagation from the irradiated spot, and it was found that grain size and shape play a decisive role.

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Section: Introductionmentioning

confidence: 99%

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

Montanari

Pakhomova

Pizzoferrato

et al. 2017

Metals

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“…In order to verify feasibility of using W coatings, various coating techniques were investigated in a coordinated R&D program launched in 2005 [8][9][10]. As a result of this program 10-15 m thick W coatings with 2-4 m Mo interlayer produced by combined magnetron sputtering and ion implantation (CMSII) technique were selected as the most reliable [11].…”

Section: Introductionmentioning

confidence: 99%

Carbide formation in tungsten coatings on carbon-fibre reinforced carbon substrates

et al. 2013

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Tungsten coatings with molybdenum interlayer deposited on carbon-fibre reinforced carbon (CFC) substrates were selected as the first wall material for the divertor in the ITERlike Wall Project at Joint European Torus. For such a layered structure, diffusion of carbon from the CFC substrate towards the Mo and W deposits is expected during the operation of the reactor. As both molybdenum and tungsten form stable carbides, brittle compounds may form at the interface, thus strongly affecting the thermomechanical performance of the coated tiles. For the purpose of prediction of the operation time of such coated tiles, carbon diffusion and carbide formation kinetics need to be determined.In the present study, W/Mo/CFC samples were subjected to heat treatment at 1470 K for various annealing times. The Focused Ion Beam technique was used for sample preparation for electron microscopy examinations. Transmission electron microscopy observations supported with diffraction pattern analyses revealed the both W 2 C and WC carbides in the W coating, as well as that of Mo 2 C carbide in the Mo layer. The results were used to estimate the kinetics of coatings degradation.2

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“…The microscopic damage consisted mainly of buckling with dimensions of 30-500 µm [10]. In this case on small areas the coating has lost the contact with the CFC substrate, but it was not removed.…”

Section: Inspection Of the W Coatings From The Ilwmentioning

confidence: 99%

Tungsten coatings under high thermal loads in JET and Magnum-PSI

et al. 2014

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During the C28-C30 campaigns the ITER-like Wall (ILW) was periodically inspected by IVIS (In Vessel Inspection System) without breaking the vacuum. After these campaigns the JET chamber was opened and the wall was inspected with a high resolution camera. The marker tiles were removed from the chamber and they have been inspected in the beryllium handling facility. The overall picture of the ILW after more than 3000 pulses looks good. However there are a few modifications such as deposition of Be on some W coated tiles, local destruction of the W coating by runway electrons in an emergency shutdown, arcing on particular W coated tiles, small delaminations on G6 and G8 divertor tiles. These aspects together with the results of high heat flux tests carried out with W coated CFC samples in Magnum-PSI are discussed in the paper.Corresponding author: Cristian Ruset,

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Tungsten coatings for the JET ITER-like wall project

Cited by 40 publications

References 10 publications

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

Laser Pulse Effects on Plasma-Sprayed and Bulk Tungsten

Carbide formation in tungsten coatings on carbon-fibre reinforced carbon substrates

Tungsten coatings under high thermal loads in JET and Magnum-PSI

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