IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Tribology Thursday Sessions
       Session TR-ThM

Paper TR-ThM4
Solution-Assisted Tribological Modification of Surfaces Using an Atomic Force Microscope

Thursday, November 1, 2001, 9:20 am, Room 132

Session: Tribological Surface Engineering for Lubrication & Wear Resistance
Presenter: J.T. Dickinson, Washington State University
Authors: R. Hariadi, Washington State University
S.C. Langford, Washington State University
J.T. Dickinson, Washington State University
Correspondent: Click to Email
When a surface is subjected to tribological loading, bonds experience time dependent distortions and spatial deformations. In the presence of simultaneous chemical stimulation (e.g., from a solution), this can lead to bond breaking, bond formation, and nuclear rearrangement. We present new studies of combining mechanical and chemical stimuli in model tribological and structural systems, particularly under conditions of solution supersaturation. Thermodynamically, the system tends towards deposition or crystal growth; we show that nucleation and growth on the surface can be controlled on the nanometer size scale using simultaneous mechanical stimulation with an AFM tip. New details of this process are presented with strong support of suggested models using analysis of small perturbations in the frictional force. Careful analysis of the"noise" in the cantilever motion during contact scanning shows that on single crystal surfaces we are very sensitive to the presence of sub-critical cluster formation and re-dissolution, we find that the amplitude of the noise increases by factors of 2-4. We take this as indirect evidence for the presence of these precursors to recrystallization. Furthermore, rich noise spectra are observed on crystal surfaces with low symmetry when one changes the scan direction—we observe modulated signals at frequencies corresponding to calculated times between asperity-lattice row encounters. Again, under supersaturation, the noise levels rise in comparison with pure solvent. Finally, we present structures and surface modifications that can be induced by these mechanical/chemical synergisms.