Benefits of Thermal Spray Coatings in Internal Combustion Engines, with Specific View on Friction Reduction and Thermal Management 2013-01-0292

The design of internal combustion engines is more and more oriented toward sustainability, especially fuel economy. To reach this aim, several technologies have been developed, however, most significantly increase engine complexity and cost. An attractive way to achieve better fuel economy is the reduction of the engine's mechanical losses, which directly has positive influence on fuel economy.

The strongest contributor to these losses is still the friction of the piston assembly. During the past decades, considerable progress in the reduction of piston and piston ring friction has been achieved. Beside the material and design of pistons and piston rings, the optimization of the liner's surface structure was always of interest, and a major role in this development was - and still is - played by surface coating technologies. The subject of this paper is the investigation of a Thermal Spray Coating, the Plasma Transferred Wire Arc (PTWA), which offers an interesting combination of several positive effects, including friction reduction and thermal benefits. This is based on the nature of the PTWA-coating, which consists of a thin layer of porous metal. The properties of this layer can be adapted by several parameters, to suit the specific requirements of the engine's application.