Abstract
One way to reduce exhaust emissions is to reduce oil consumption. Piston rings largely contribute to oil consumption regulation as they ensure the oiltightness between the combustion chamber and the cylinder crankcase. Efficiency should be constant during all the engine lifetime. Therefore, the piston ring wear must be very low.
Specific surface treatments on the running side are used to guarantee a low wear, and durable piston rings. Among all the available surface treatments, the choice of a specific one depends on the application, the manufacturing process and of course the cost.
It is very important to take into account, from the beginning of the development, the environmental aspects of the process. Thermal spray, nitriding and vacuum technologies satisfy at least two of the main requirements: the performance and the environmentally safe process.
Tests on samples coupled with engine tests help to characterise the tribological behaviour of coatings.