One important development area for obtaining better fuel economy is to reduce mechanical friction losses in engine components. The power cell and the valve train components are a significant source of mechanical friction loss in an automobile engine. A lot of attention has been given to the development of new materials and coatings that not only minimize friction, but also improve wear resistance. Amorphous carbon (a-C:H, a-C:H:Me and a-C:H;X) known as DLC (Diamond-Like-Carbon) coatings have a high potential to fulfill these requirements, providing significant potential for a solution under these demanding service conditions.
This paper presents the evaluation of DLC coatings on piston rings, liners, pins and cam-followers. It will be presented results of different coating systems, designed for each application. It is also discussed the coating engineering required due to the particular running conditions of each product.
Detailed bench tests and metallurgical characterization and engine tests are presented.