Dynamic Friction of Nanoscale Sliding on a C₆₀Deposited Film

Abstract

We measured the frictional behavior acting on C60 films at a small normal load as a function of oscillation amplitude using a MHz-range quartz crystal resonator and an optical AFM cantilever. The frictional behavior for C60 films varies by the amplitude: For the amplitudes smaller than the C-C bond length of the C60 molecule, the dynamic frictional force is directly proportional to the amplitude, while it becomes almost constant for larger amplitudes. Although the observation is in qualitatively the same manner as HOPG, the dynamic frictional force for small amplitudes is significantly larger than that of HOPG. This difference suggests that C60 molecules easily tilt and/or rotate when the tip slides in C60 films, and the dynamic friction arises from the tilting and/or rotating motion.

Superlubricity of Fullerene Derivatives Induced by Host–Guest Assembly

“…This may be attributed to two factors according to the structural properties of fullerene molecules. On the one hand, fullerene molecules could act as molecular bearings during the rubbing process. − Miura et al have also proposed a stick–slip rolling model with a step rotation of a C 60 molecule to reveal the detailed mechanism. On this basis, the lubrication mechanism model is presented as shown in Figure b,c.…”

Integrated QCM-Microtribometry: Friction of Single-Crystal MoS2 and Gold from μm/s to m/s

“…However, so few of these measurements exist in the literature that there has been virtually no experimental support for this theoretically supportable hypothesis. This is important because a variety of mechanical systems have been used to implement QCM-based friction measurements of solid-on-solid contacts, including atomic force microscopes, ,,, scanning tunneling microscopes, , nanoindentation, , surface forces apparatus, and dedicated normal force or displacement transducers to engage a sphere with the QCM surface. ,,, Another approach is to attach three spheres to a weighted plate and set the assembly onto the QCM. ,,, We note that most of these prior experiments have studied the partial slip regime, although several different groups have observed the transition from partial to full slip. − ,, Only two previous studies have reported quantitative measurements of kinetic friction in full slip conditions using the energy dissipation technique used here. , The results of this study experimentally support the hypothesis that QCM-based friction measurements are insensitive to the mechanical attributes of the measurement system. This outcome suggests (1) that QCM-based friction results can be safely compared between studies and (2) that the QCM-based approach can be integrated with any existing spring-based instrument (e.g., AFM or microtribometer).…”

“…However, so few of these measurements exist in the literature that there has been virtually no experimental support for this theoretically supportable hypothesis. This is important because a variety of mechanical systems have been used to implement QCM-based friction measurements of solid-onsolid contacts, including atomic force microscopes, 31,32,39,40 scanning tunneling microscopes, 35,38 nanoindentation, 27,41 surface forces apparatus, 42 and dedicated normal force or displacement transducers to engage a sphere with the QCM surface. 28,30,34,37 Another approach is to attach three spheres to a weighted plate and set the assembly onto the QCM.…”

“…The quartz crystal microbalance (QCM) provides a fundamentally distinct technique for quantifying friction. − Its most unique attribute is the ability to probe nano- and microscale friction at high slip speeds consistent with those found in many practical applications. Relative to spring-based methods, it is a less common, yet complementary and equally powerful tool for quantifying friction in nanoscale and microscale tribology measurements. − In a QCM-based measurement, changes in the resonance frequency and quality factor of the QCM are used to quantify friction forces, frictional energy dissipated, slip lengths, contact areas, contact pressures, and shear strengths within static, partial slip, and full slip contact interfaces. − ,− Because the QCM resonates at extremely high frequencies (often exceeding 1 MHz), even the smallest slip lengths create slip speeds that approach 1 m/s; , as a result, there is an enormous speed gap between friction measurements made with spring-based instruments and those based on QCM resonance. Inertial effects provide another important distinction between these methods.…”

Effects of Relative Humidity on Lubricating Properties of Ionic Liquids

“…Therefore, lubricants are being developed to reduce the friction losses in these systems. Lubricants can be categorized as solid lubricants [2][3][4], semisolid lubricants [5], and liquid lubricants [6][7][8]. Liquid lubricants under boundary lubrication reduce friction and wear by forming an adsorption and reaction layer at the friction interface.…”