Investigation of liner samples exposed to an in-situ carbidization in TEXTOR

• Published in: Journal of nuclear materials 1985-10, Vol.136 (1), p.124-128
• Main Authors: Besocke, K.H., Flentje, G., Winter, J., Wienhold, P., Esser, H.G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Magnetic confinement and equilibrium; Materials science; Metals, semimetals and alloys; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Production techniques; Specific materials; Surface treatment
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/0022-3115(85)90038-8

A plasmachemical in-situ technique for the deposition of carbon on limiters and first wall of the tokamak TEXTOR has been developed. RG-discharge in a throughflow of hydrogen with admixed 1.5% methane has been used to implant methane ions into the limiters and wall. Different-samples (Inconel 600) in liner position have been exposed and afterwards analyzed with SIMS and AES. It has been shown that during the plasmachemical carbon deposition at 240°C predominantly chromium carbide was formed in the surface near layer. Nickel carbide was traced in a negligibly small amount. Depth profiles indicate an exponential dependence of the chromium carbide concentration up to a depth of about 10 nm. This is in agreement with the estimated diffusion profile of carbon; literature values of the carbon diffusivity in Ni, Ni-Cr and Ni-Co alloys yield a mean characteristic diffusion length of about 8 nm. The total amount of deposited carbon as determined from AES measurements is 6 × 10 15 atoms cm −3 , in reasonable agreement with 1.2 × 10 16 cm −2 as determined from the partial pressure balance during the carbidization process.