Thermal Spraying of Nano-Crystalline Coatings for Al-Cylinder Bores 2008-01-1050

The fuel consumption of modern passenger cars can be reduced by utilizing lightweight construction as well as by decreasing internal friction losses in the drive train. Modern engine blocks are partly made of cast iron or alumimum material whereas for the later hypo-eutectic AlSi-alloys dominate. Due to the low hardness, surfaces made of these alloys cannot be used as a friction partner for the piston rings. Cast iron liners are often inserted into the engine block to provide a wear-resistant surface for the piston rings. This work describes how cast iron liners can be replaced by thin, nanocrystalline iron based coatings in order to decrease friction losses as well as reduce the engine weight. The coatings were applied by thermal spraying with the Plasma Transferred Wire Arc internal diameter coating system.