Tuning the Friction of Silicon Surfaces Using Nanopatterns at the Nanoscale

Abstract

Friction and wear become significant at small scale lengths, particularly in MEMS/NEMS. Nanopatterns are regarded as a potential approach to solve these problems. In this paper, we investigated the friction behavior of nanopatterned silicon surfaces with a periodical rectangular groove array in dry and wear-less single-asperity contact at the nanoscale using molecular dynamics simulations. The synchronous and periodic oscillations of the normal load and friction force with the sliding distance were determined at frequencies defined by the nanopattern period. The linear load dependence of the friction force is always observed for the nanopatterned surface and is independent of the nanopattern geometry. We show that the linear friction law is a formal Amontons' friction law, while the significant linear dependence of the friction force-versus-real contact area and real contact area-versus-normal load captures the general features of the nanoscale friction for the nanopatterned surface. Interestingly, the nanopattern increases the friction force at the nanoscale, and the desired friction reduction is also observed. The enlargement and reduction of the friction critically depended on the nanopattern period rather than the area ratio. Our simulation results reveal that the nanopattern can modulate the friction behavior at the nanoscale from the friction signal to the friction law and to the value of the friction force. Thus, elaborate nanopatterning is an effective strategy for tuning the friction behavior at the nanoscale.

Probing the frictional properties of soft materials at the nanoscale

“…A series of MD simulations was used to study the frictional behaviour of nanopatterned silicon surfaces and how nanopatterning can be used to tune friction at the nanoscale. 135 It was found that for nanopatterned surfaces, there is always a linear dependence of load on the frictional forces, both for adhesive and non-adhesive surfaces, which is independent of the nanopattern geometry. This can represent Amontons' law (eqn (1)) and it's relation to the real contact area.…”

Tribology of 2D Nanomaterials: A Review

“…Second, micro/nano patterns can efficiently reduce the actual contact area, therefore also reduce the friction efficiency and wear rate. However, the current understanding of the friction behavior on micro/nano textured surface is not sufficient [130]. One reason is the lack of precise tools to study nanoscale friction.…”

Thermal-Controlled Frictional Behaviour of Nanopatterned Self-assembled Monolayers as Triboactive Surfaces

“…Triboactive surfaces stand for surfaces with controlled frictional behaviour finely tuned in real time by using external stimuli as temperature [9,10], laser beam [11], UV or IR beams [12,13], electric or electrostatic fields [14,15] and many other ways [16,17]. For instance, photo-and thermo-activated self-assembled monolayers (SAM) seem to be a promising way for this purpose [9,10,11,12,13] assuming that suitable functional groups can be found or synthesized for each given application.…”