Superlubricity of glycerol by self-sustained chemical polishing - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Scientific Reports Année : 2019

Superlubricity of glycerol by self-sustained chemical polishing

Résumé

An impressive superlow coefficient of friction (CoF) as low as 0.004 (nearly equivalent to the rolling coefficient) was obtained by sliding a steel ball against a tetrahedral amorphous diamond-like carbon (ta-C) coating in glycerol under a boundary lubrication regime. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) revealed substantial changes in the surface chemistry and topography in the friction track. As shown by XPS analysis, a transfer of iron atoms from the steel ball to the ta-C layer occurred, forming iron oxy-hydroxide (FeOOH) termination on both surfaces. Between them, theoretical calculations show that a nanometre-thick fluid film consisting of glycerol and its degradation products prevents direct contact between the solid surfaces by nm-thick film EHL lubrication and results in the superlow friction, in agreement with the experiment. Furthermore, molecular dynamics (MD) simulations reveal that hydrogen atoms act as "low-friction brushes" between sliding layers of crystalline FeOOH, resulting also in low friction. A new model of sustainable green superlubricity is proposed. The tribo-formation of FeOOH with glycerol leads to a unique polishing process, which in turn leads to a self-sustained Elasto-Hydrodynamic Lubrication (EHL) regime until the very thin fluid film is no more than a few nanometres thick. At lower thicknesses, the hydroxide layer takes over. Wear of the ta-C coating is negligible, while wear on the steel ball is very moderate and acceptable for many practical applications, such as bio-tribology and the food industry, in which green lubrication is especially needed.

Domaines

Matériaux
Fichier principal
Vignette du fichier
LONG_DeBARROS-BOUCHET_LUBRECHT_et_al_2019.pdf (2.38 Mo) Télécharger le fichier
Origine : Publication financée par une institution
Loading...

Dates et versions

hal-02110944 , version 1 (25-04-2019)

Licence

Paternité

Identifiants

Citer

Yun Long, Maria-Isabel De Barros Bouchet, Ton Lubrecht, Tasuku Onodera, Jean-Michel Martin. Superlubricity of glycerol by self-sustained chemical polishing. Scientific Reports, 2019, 9, pp.6286. ⟨10.1038/s41598-019-42730-9⟩. ⟨hal-02110944⟩
54 Consultations
40 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More