Absolute quantitative data from atomic force microscopy (AFM)/lateral force microscopy experiments are always difficult to obtain mainly due to the need of the normal force $F_N$ and the friction force $F_F$ calibration. In this article, we developed an experimental method which allows us to extract absolute quantitative friction data without calibrating any force when the relation between $F_N$ and $F_F$ is linear or only calibrating the normal force when the relationship is nonlinear. The technique reported here, is suitable for an atomic force microscope that has the cantilever attached to the piezotube translator and an unguided incident laser beam on the cantilever. We take advantage of the piezotube bending during a large scan (5 μm×5 μm), generally considered as an undesirable effect, to calculate a detection factor that allows the determination of quantitative tribological data. The validity of our experimental method is checked on the extensively AFM studied materials, such as muscovite, silicon, and highly oriented pyrolytic graphite. The experiments are carried out in a load range where the shear stress τ can be expressed as ${\mathrm{\tau =\tau }}_0\mathrm{+\mu P,}$ where μ is the friction coefficient, P is the mean contact pressure, and ${\tau }_0$ is a parameter related to the tip/sample adhesion. The value of μ is found to be independent of the tip geometry and the pull-off force, and always constant for a given tip/sample couple in the load range investigated.

This article focused on the effects of the presence of liquid on tribological performances of graphite and hexagonal boron nitride (hBN) particles at ambient atmosphere. Two tribological tests conditions have been evaluated with AISI 52100 steel materials. In dry conditions for lubrication tests with pure particles and liquid conditions a drop of liquid is added before or during the friction tests. In dry conditions, graphite and hBN have two different tribological performances, while whatever was the type of liquid in liquid conditions, they are similar: μpure graphite ≈ 0.09 and μpure hBN ≈ 0.42, while μgraphite+liquid ≈ μhBN+liquid ≈ 0.06. Raman spectroscopy and scanning electron microscopy (SEM) investigations bring out weak influence of sliding mechanical constraints for tribofilms built in the presence of the liquid. Different hypotheses have been investigated; tribo-intercalation, influence of adsorption, lubrication by hydrogen, and action of the liquid. The simultaneous presence of liquid and particles induces friction mechanism inside the tribofilm reducing friction due to its nanostructuration.