Direct measurement of plowing friction and wear of a polymer thin film using the atomic force microscope

Abstract

Nanometer-scale plowing friction and wear of a polycarbonate thin film were directly measured using an atomic force microscope (AFM) with nanoscratching capabilities. During the nanoscratch tests, lateral forces caused discrepancies between the maximum forces for the initial loading prior to the scratch and the unloading after the scratch. In the case of a nanoscratch test performed parallel to the cantilever probe axis, the plowing friction added another component to the moment acting at the cantilevered end compared to the case of nanoindentation, resulting in an increased deflection of the cantilever. Using free-body diagrams for the cases of nanoindentation and nanoscratch testing, the AFM force curves were analyzed to determine the plowing friction during nanoscratch testing. From the results of this analysis, the plowing friction was found to be proportional to the applied contact force, and the coefficient of plowing friction was measured to be 0.56 ± 0.02. Also, by the combination of nanoscratch and nanoindentation testing, the energetic wear rate of the polycarbonate thin film was measured to be 0.94 ± 0.05 mm 3 /(N m).

Scratch Resistance and Localised Damage Characteristics of Polymer Surfaces – a Review

“…The scratch test has potential for use with ultra-thin [66] and composite-layered surfaces. At present, this test has been applied to coatings and thin films where specific energy to initiate cracking is used as a key parameter.…”

Microscale frictional response of bovine articular cartilage from atomic force microscopy

“…Microscale tribological and mechanical material properties such as surface roughness, wear, friction, elastic modulus, and boundary lubrication have been studied on engineering and biological surfaces by AFM (Bhushan and Koinkar, 1996;Du et al, 2001). However, the tribological and mechanical material properties of articular cartilage have not yet been well characterized at microscale levels, neither have the relationships between microscale properties or between micro-and macroscale properties.…”

An integrated approach towards the study of scratch damage of polymer

“…[28][29][30][31] Scanning probe microscopy instruments, such as the atomic force microscope, [32][33][34] have also been adopted and improvised by researchers to perform scratch tests at a nanometer scale. For evaluating the scratch surface and subsurface, researchers have used equipment like the optical microscope (OM), 18,24,26 atomic force microscope, 24,26,32,[35][36][37][38] scanning electron microscope, 14,15,26,39,40 X-ray photoelectron spectroscope, 41 laser confocal microscope, 18 Raman spectroscope, 28 white-light interferometer, 20,24 profilometer, 14,15,42 tribometer, 43 ellipsometer, 28 and scanner. 17,44,45 A review of the scratch test devices available for macroscopic testing 46 readily reveals that the ranges of normal loads and scratch rates for most devices are rather limited, while some of them may only be good for the evaluation of marred surfaces and, thus, insufficient for the scratch studies.…”