Dresden 2006 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

VA: Vakuumphysik und Vakuumtechnik

VA 2: Surfaces, instruments and systems

VA 2.2: Vortrag

Montag, 27. März 2006, 11:00–11:20, HSZ 101

STM study on surface modifications on vacuum fired 304L stainless steel — •Axel Stupnik and Manfred Leisch — Institute for Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria

In UHV and XHV applications high temperature bakeout (vacuum firing) is a common method to reduce the hydrogen outgassing rate from stainless steel surfaces. This procedure reduces the amount of hydrogen in the bulk. At low bulk concentration hydrogen outgassing is basically limited by surface recombination. The surface of glass bead blasted 304L steel samples was investigated by STM after normal bakeout procedure at 300^∘C and after vacuum firing at 1000^∘C. During vacuum firing a complete reconstruction of the surface can be observed. Already after 5 min of vacuum firing the formation of (111) terraces with monoatomic steps can be found. Slightly tilted crystallites exhibit (111) terraces intersected by bunched steps and facets. These facets form a nearly regularly pattern corresponding in orientation almost to the (100) and (110) planes. After 15 min vacuum firing large (111) terraces with extensions up to 200nm intersected by bunched steps can be observed. The general appearance of the surface after vacuum firing indicates a significant reduction of active sites for recombination of hydrogen. This supports the present understanding of outgassing for this material.

Supported by Zukunftsfonds des Landes Steiermark.