Effects of Diamond-like Carbon and Tungsten-Carbide Carbon Coatings on Tribological Performance of Cam–Tappet Conjunction

Abstract

Cam–tappet contacts are responsible for ~7.5% of the internal combustion engine’s (ICE) total frictional losses. The application of coatings can improve the tribological performance of these contacts. In this paper, the application of a WC-C coating as a novel approach for cam–tappets in comparison with DLC coating is investigated. The tribological performance of the coated contacts are evaluated by a novel model comprising combined implicit analytical and explicit numerical methods. This model considers the coupled tribo-dynamic behaviour whilst obtaining detailed tribological performance. The combined approach provides a computationally efficient platform. The results show that application of DLC or WC-C can improve the film thickness value by up to 41%. They can improve boundary friction, whilst increasing the viscous friction.

Keywords

• cam–tappet contact
• DLC and WC-C
• tribo-dynamics
• coated EHL