Friction of thin water films: a nanotribological study

摘要: Abstract Lubricant thickness is known to influence the frictional properties between two contacting surfaces in relative motion. In this paper, dependence of friction on water films with various thicknesses examined using a scanning force microscopy (SFM) hydrophilic silicon tip and flat that was rendered either or hydrophobic. Results indicate are influenced by ordering effects water. The surface initially covered 2.6 nm as function film thickness, which separately determined tunneling dynamic SFM. Capillary dominate tribological for 3 about 1 thick. For thinner can be explained effect sample tip, together cause an increased resistance shear (higher viscosity). Further reduction due desorption leads decrease force; regime dominated cohesive forces arising from solid–solid contact. all applied study, liquid confinement does not occur. Rather, sharp SFM apparently penetrates apex making direct contact surface. occurs at sides tip. These results, previous microtribological studies, highlight significant differences existing moving motion micro- nanoregime.