Long-lasting solid lubrication by CNT-coated patterned surfaces

Abstract

The use of lubricants (solid or liquid) is a well-known and suitable approach to reduce friction and wear of moving machine components. Another possibility to influence the tribological behaviour is the formation of well-defined surface topographies such as dimples, bumps or lattice-like pattern geometries by laser surface texturing. However, both methods are limited in their effect: surface textures may be gradually destroyed by plastic deformation and lubricants may be removed from the contact area, therefore no longer properly protecting the contacting surfaces. The present study focuses on the combination of both methods as an integral solution, overcoming individual limitations of each method. Multiwall carbon nanotubes (MWCNT), a known solid lubricant, are deposited onto laser surface textured samples by electrophoretic deposition. The frictional behaviour is recorded by a tribometer and resulting wear tracks are analysed by scanning electron microscopy and Raman spectroscopy in order to reveal the acting tribological mechanisms. The combined approach shows an extended, minimum fivefold longevity of the lubrication and a significantly reduced degradation of the laser textures. Raman spectroscopy proves decelerated MWCNT degradation and oxide formation in the contact. Finally, a lubricant entrapping model based on surface texturing is proposed and demonstrated.

Elastic Damper Based on the Carbon Nanotube Bundle

“…Moreover, CNTs are flexible, lightweight, good heat and electricity conductors, thus being useful in a number of applications [12][13][14][15]. The most important mechanical applications of CNTs are high-strength ropes [2,16], fibers [17][18][19][20][21], polymer-and metal-matrix composites [22][23][24], solid lubricants [24,25], etc.…”

Adsorption of Nonylphenol to Multi-Walled Carbon Nanotubes: Kinetics and Isotherm Study

“…While the S BET of the modified MWCNTs was comparable with those reported by others [43][44][45], the pore volume was much higher; 0.81 cm 3 /g was obtained ( Table 2). HNO 3 treatment reduced metals on the surface of MWCNTs and created new acidic sites, which dominate the roughness of the MWCNTs [46]. Figure 2a gives the SEM (left) and TEM (right) images of raw MWCNTs, respectively.…”

Friction and Tribo-Chemical Behavior of SPD-Processed CNT-Reinforced Composites

“…After removal, the COF increased, whereas in the composite the COF reduction is pronounced up to 20,000 cycles due to a continuous supply of CNT to the contact zone. Nevertheless, CNT coatings produced on laser-patterned surfaces showed a long-lasting solid lubrication, due to CNT entrapping inside the laser textures serving as lubricant reservoirs [20].…”