Surface characterization of CVD tungsten coating on molybdenum substrate

Du, Jie; Li, Zhengxiang; Liu, Gaojian; Zhou, Hui; Chun-liang, Huang

doi:10.1016/j.surfcoat.2004.10.130

Cited by 31 publications

(8 citation statements)

References 1 publication

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“…In the present research, molybdenum was used as a successfully interlayer, although it is a carbide former like W. The use of Mo as a substrate for W coatings was previously reported in the literature [15,16], but no one has used Mo as an interlayer for W coating on CFC. A beneficial role of Mo seems to be in connection with the adjustment of the thermal expansion mismatch between CFC and W (α W = 4-5⋅10 -6 K -1 ; α CFC = 10-12⋅10 -6 K -1 perpendicular to fiber and 0-1⋅10 -6 K -1 parallel to fiber plane; α Mo = 7.2⋅10 -6 K -1 ).…”

Section: Depositionmentioning

confidence: 90%

Tungsten coatings deposited on CFC tiles by the combined magnetron sputtering and ion implantation technique

et al. 2007

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Combined Magnetron Sputtering and Ion Implantation (CMSII) is a deposition technique involving simultaneously magnetron sputtering and high energy ion bombardment of the coating during its growth. A high voltage pulse discharge (U = 40 kV, τ = 20 µs, f = 25 Hz) is superposed over the magnetron deposition and by this way, positive ions are accelerated to the components to be coated, bombarding initially the substrate and then the coating itself. In the framework of the ITER-like Wall Project this method was applied to produce nanostructured W coatings on the CFC (Carbon Fibre Composite) substrate. These coatings have been characterized in terms of adhesion, thickness, structure and resistance to high thermal loads (up to 23.5 MW/m 2). Based on the results of these tests, which are presented in this paper, CMSII technology was selected for coating about 1,100 tiles with 10 µm tungsten layer for the JET first wall and divertor.

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Section: Depositionmentioning

confidence: 90%

Tungsten coatings deposited on CFC tiles by the combined magnetron sputtering and ion implantation technique

et al. 2007

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“…However, PS limit is represented by the inability to finely control film structure at the atomic scale, which often results in undesired material properties and failure of the coating [9,10]. Alternatively, in order to finely control film structure, morphology and stoichiometry, a variety of physical-(PVD) and chemical-(CVD) vapour deposition techniques is available for W coatings deposition [11,12,13,14]. Pulsed Laser Deposition (PLD) is one of the most versatile PVD techniques, by which both mono-or multi-elemental films such as metals, compounds and carbon based materials, also replicating complicated or unusual target stoichiometry can be deposited [15,16,17,18,19,20,21].…”

Section: Introductionmentioning

confidence: 99%

Amorphous, ultra-nano- and nano-crystalline tungsten-based coatings grown by Pulsed Laser Deposition: mechanical characterization by Surface Brillouin Spectroscopy

et al. 2016

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Pulsed Laser Deposition allows to obtain W and W-Ta alloy coatings with different nanostructures, monitored by X-ray diffraction. The correlation between such structures and the elastic properties is investigated for amorphous-like, ultra-nano-and nano-crystalline coatings obtained by tuning the gas pressure during deposition, annealing temperature and Ta concentration. The full elastic characterization is achieved by surface Brillouin spectroscopy, interpreted by isotropic and anisotropic film models. Amorphous like coatings are obtained with He pressures of tens of Pa. In comparison with bulk W, they have lower stiffness, by about 60%, closely correlated to the mass density (lower by about 40%). In the nanocrystalline regime the stiffness is more correlated to the average grain size, approaching the bulk values for increasing crystallite size. Vacuum annealing of amorphous like coatings leads to the nucleation of ultra-nano crystalline seeds, embedded in an amorphous matrix with intermediate values for mass density and stiffness. Here, the stiffness results from an interplay between the crystal size and the density. Alloying with Ta leads to properties which are consistent with the lever rule in the nanocrystalline regime, and deviate from it when the higher Ta concentration, interfering with crystal growth, induces an ultra-nano crystalline structure.

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“…The investigated samples in the current work had the configuration of W on a Mo interlayer with different substrates. The use of the Mo interlayer as a substrate for W was previously reported in the literature, expressing it as an advantage [31]. Also, the Mo interlayer was applied as a buffer for the thermal expansion mismatch between the W layer and the low Z material substrate [31].…”

Section: Investigated Samplesmentioning

confidence: 99%

Enhanced XRF Methods for Investigating the Erosion-Resistant Functional Coatings

2019

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The development of erosion-resistant functional materials usable as plasma facing first wall components (PFC) is crucial for increasing the lifetime of future fusion reactors. Generally, PFCs have to be quality checked and characterized regarding their composition, before integrating them into the fusion reactor vessel. Enhanced X-ray fluorescence (XRF) methods represent an effective alternative to conventional analysis methods for the characterization of refractive metallic coatings on large areas of fusion materials. We have developed and applied XRF methods as fast and robust methods for the characterization of the thickness and composition uniformity of complex functional coatings. These coatings consist of tungsten included in multilayer configuration and deposited on low or high Z substrates. We have further developed customized calibration protocols for quantifying the element composition and layer thickness of each investigated sample. The calibration protocols are based on a combination of standard samples measurements, Monte Carlo simulations, and fundamental parameter theoretical calculations. The calibrated results are discussed considering a selection of relevant PFC samples. The deposition uniformity was successfully investigated for different PFC-relevant tiles and lamella shaped samples with W layers below and over the W L-line saturation thickness. Also, the 2D thickness mapping capability of the XRF method was demonstrated by studying the plasma post-erosion pattern.

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Surface characterization of CVD tungsten coating on molybdenum substrate

Cited by 31 publications

References 1 publication

Tungsten coatings deposited on CFC tiles by the combined magnetron sputtering and ion implantation technique

Tungsten coatings deposited on CFC tiles by the combined magnetron sputtering and ion implantation technique

Amorphous, ultra-nano- and nano-crystalline tungsten-based coatings grown by Pulsed Laser Deposition: mechanical characterization by Surface Brillouin Spectroscopy

Enhanced XRF Methods for Investigating the Erosion-Resistant Functional Coatings

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