Ultra-Low Friction on Tetrahedral Amorphous Diamond-Like Carbon (ta-C) Lubricated with Ethylene Glycol

Abstract

Lubricated tetrahedral amorphous carbon coatings can show a very complex tribological behavior. In particular, friction regimes with extremely low friction have been observed. In tribological experiments with a ta-C/steel friction pair that was lubricated with ethylene glycol, we observed a sudden and very strong decrease in the effective friction coefficient from 0.45 to 0.01 after running-in. By varying different components of the tribological system after this abrupt decrease we investigated the role of the counter-body, the lubricant and the coating. To investigate the surface chemistry, static time-of-flight secondary ion mass spectrometry (ToF-SIMS), dynamic secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS) measurements were performed. Using deuterated lubricants, ToF-SIMS measurements allowed us to distinguish adsorption of hydrogen and hydroxyl-groups from the lubricant from the adsorption from the environment. Deuterated hydroxyl-groups from the lubricant adsorbed to the surface during the experiment. In particular, more adsorbed deuterated hydroxyl-groups were detected prior to the sudden decrease in the friction coefficient. Thus, the sudden decrease in the coefficient of friction was most likely caused by an interplay between the lubricant, the ta-C coating and the counter-body which lead to the formation of transfer and adsorption layers.

Tribological performance of aUHMWPE‐based multiscale composite under different lubrication and loads

“…This is supported by the fact that Neat and Multiscale samples exhibit almost identical friction under EAL lubrication at both 5 and 10 MPa. Similar excellent lubrication by aqueous solutions of glycerol and water has been demonstrated in other studies 21,65,66 . No distinct deposit or transfer layers could be found on the wear tracks of the tested materials.…”

“…Similar excellent lubrication by aqueous solutions of glycerol and water has been demonstrated in other studies. 21,65,66 No distinct deposit or transfer layers could be found on the wear tracks of the tested materials. The EAL interferes with the self-lubricating properties of the polymer, yet favourable friction and wear performance can be obtained.…”

Galling-Free Forming of Titanium and Titanium Alloys Using Carbon-Supersaturated Tool Steel Dies

“…Figure 1 compares three methods for in situ solid lubrication [8]. The chlorineimplanted TiN and TiCN coatings had anti-galling capacity due to in situ formation of deformable titanium oxide (TiO x for 1 < x < 2) film on the contact interface [9][10][11], as depicted in Figure 1 a. Tetragonal DLC (t-a:C) coating, working in the tailored polymer lubricant, hindered the direct contact of work materials with DLC coating by in situ synthesis of polymer layer to attain the superlubrication conditions [12], as illustrated in Figure 1b. Using the carbon supersaturated ceramic, stainless steel and tool steel dies, the isolated carbon film from CS-dies was in situ formed on the contact die-work interface to lower the friction and wear [13][14][15][16][17][18].…”