Dresden 2009 – wissenschaftliches Programm

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VA: Fachverband Vakuumphysik und Vakuumtechnik

VA 2: Ultra-high vacuum UHV

VA 2.2: Vortrag

Montag, 23. März 2009, 12:35–12:55, HSZ 101

AFM, STM and Atom Probe study on vacuum fired 316 LN stainless steel — Paul Frank¹, Lars Westerberg², and •Manfred Leisch¹ — ¹Institut für Festkörperphysik, TU Graz, 8010 Graz, Austria — ²Department of Physics, Uppsala University, SE 751 21 Uppsala, Sweden

Stainless steel is one of the most used construction materials in vacuum technology. In order to reduce the outgassing of hydrogen a high temperature treatment (vacuum firing) is a common used method especially in XHV applications. Since the outgassing process is strongly related to surface morphology the surface of grade 316 LN stainless steel, after low temperature bake-out process and vacuum annealing, has been studied by atomic force microscopy (AFM) and scanning tunnelling microscopy (STM). The local elemental composition on the surface before and after thermal treatment has been investigated by atom probe (AP) depth profiling measurements. After vacuum annealing AFM and STM show distinct changes in the surface structure and topology. Compared to previous studies on grade 304 L stainless steel recrystallisation and surface reconstruction is less pronounced on the 316 LN material. AP depth profiling analyses result in nickel enrichment on the surface. Since hydrogen recombination is almost controlled by surface structure and composition the experimental results will be discussed with respect to the influence on the outgassing behaviour.

(Work supported by Zukunftsfonds des Landes Steiermark P 119).