Atomic-scale tribometer for friction studies in a controlled atmosphere

Abstract

Abstract To obtain a more fundamental understanding of macroscopic tribological processes, investigations on a microscopic or even atomic scale have to be undertaken. Macroscopic mechanical concepts of adhesion and friction phenomena are not adequate for explaining “nanomechanics”. The development of local probe techniques (scanning tunneling microscopy, atomic force microscopy) offered powerful new tools for studying microscopic, i.e. local, surface properties. One possible application of these instruments is local friction investigation by simulating a single asperity contact of a real surface with an atomic force microscope tip, and measuring normal and lateral forces occurring at the tip while imaging a sample. With respect to the enormous effect of environmental conditions on which local tribological interactions take place, rigorous control of the atmosphere is needed. We present details of an instrument suited for carrying out local friction investigations in controlled atmospheric conditions or on samples embeded in an extended experimental environment. The instrument's conception and possible applications are described, especially its combination with an electrochemical cell and potentiostatic control of a sample immersed in electrolytes. First results obtained with such a set-up are presented.