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O: Fachverband Oberflächenphysik

O 75: Nanotribology II

O 75.2: Vortrag

Donnerstag, 25. März 2010, 15:15–15:30, H36

Frictional changes upon modification of single crystal electrodes with anions — •Florian Hausen and Roland Bennewitz — INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken

Considering that most tribological processes occur at a solid - liquid interface, friction measurements under electrochemical conditions are scarce. Compared to similar experiments in ultra high vacuum the surfaces are as clean and well defined. A unique tool offered by electrochemical methods is the possibility to alter the surface structure and to deposit various adsorbates by changing the applied potential at the working electrode.

We present friction force measurements on Au(111) and Au(100) single crystal electrodes performed by means of atomic force microscopy (AFM). The influence of a surface modification with anions is explored by using electrolytes containing sulphate. With adsorbing sulphate to the surface a strong increase of the friction force compared to the bare gold substrate is found. Furthermore we observe a strong correlation between friction forces and the anion structure. Complementary studies were done by using perchlorate, which is isoeletronical to sulphate but shows a different electrochemical behaviour. Additionally the effect of chloride on friction and wear due to the enhanced mobility of the surface atoms in the presence of chloride will be discussed.