Rising oil prices and ecological aspects as the CO₂ emissions causes a strong demand for a decrease in fuel consumption for engines in passenger cars and trucks.
Tribofunctional coatings applied to gray cast iron and light metal cylinder liners by HVOF and HVSFS are able to reduce the friction in the system liner and piston rings. A reduction in oil consumption also decreases emissions. The HVOF technique was chosen because it produces an advantageous coating microstructure and performs a good adhesion to the substrate.
Spray coatings were carried out using a conventional HVOF torch that is manipulated by a six axis robot allowing for improved kinematic programs. Liners and  engine blocks were manipulated using a specially developed rotary table.
Single gray cast iron liners used in truck engines, single light metal test liners and four cylinder engine blocks for passenger cars were coated with different materials such as metals, cermets and oxides by HVOF and HVSFS processes. Coatings were tested for friction and wear reduction in oscillating friction wear tests and fired engine tests. Results are compared to state of the art cylinder liners.