• Raisin, Jonathan
• Vergne, Philippe
• Fillot, Nicolas
• Dureisseix, David

Abstract

In recent years, Diamond-like carbon (DLC) coatings have been increasingly used in tribological applications thanks to their ability to mitigate friction. Among other factors, the low thermal conductivity of these coatings was shown to play a significant part, especially in the EHL regime. By disrupting the heat removal, the presence of DLCs or other low thermal inertia coatings induces higher temperatures in the central region of the contact than for steel-steel configurations. These higher temperatures in turn lead to a reduction in viscous friction without notable consequences on the film thickness. While valid for low to moderate sliding conditions, this statement however does not apply to infinite sliding conditions where the temperature balance strongly affects the film thickness through the so-called “thermal viscosity wedge mechanism”. The present work therefore investigated the influence of low thermal inertia coatings on the lubrication of contacts operating under infinite sliding conditions. Thermal Elastohydrodynamic (TEHD) simulations of circular steel-steel contacts with and without low thermal inertia coatings were performed. Pressure and film thickness profiles as well as temperature distributions obtained in both configurations with a Newtonian lubricant were compared and analyzed. Results show that the use of low thermal inertia coatings tends to counteract the thermal viscosity wedge mechanism and result in lower central and minimal film thicknesses in infinite sliding conditions.

Topics

• Carbon
• simulation
• steel
• viscosity
• thermal conductivity