@phdthesis{Ma2021,
  author    = {Haoran Ma},
  title     = {Nanotribology of metallic glasses in corrosive environments},
  address   = {Saarbr{\"u}cken},
  doi       = {10.22028/D291-34188},
  url       = {https://nbn-resolving.org/urn:nbn:de:bsz:291:415-2213},
  pages     = {VII, 121 S.},
  year      = {2021},
  abstract  = {Metallic glasses (MGs) are promising materials for micromechanical systems, where miniaturized components involving mechanical contact require control of friction. Nanotribological experiments on MGs in corrosive aqueous solutions are carried out using atomic force microscopy (AFM), focusing on the role of surface oxide films formed during corrosion. A new method is developed to study in situ the structure of surface oxide films. The surface oxide film has a bilayer structure as revealed by repeated scanning with the AFM tip. The dependence of friction on electrochemical potential reveals the growth mechanism of the oxide film. Friction and adhesion after different immersion times in different solutions allow to compare the physicochemical processes of surface dissolution at the interfaces of the two layers of surface films and elucidate their influence on friction. An irregular atomic-scale stick-slip friction is observed and attributed to the amorphous nature of corroded surfaces. Finally, we show three different friction processes occurring at increasing normal loads: removal of the dissolution layer at low-load regime; stress-assisted tribo-oxidation in intermediate-load regime; and tribochemical wear in high-load regime. The chemical sensitivity of nanotribology studies demonstrates a novel route to explore fundamental mechanisms of corrosion at the microscopic scale.},
  language  = {en}
}