The project ALICE is directed to the development of a new combustion engine system consisting of an optimised combination of piston, piston ring and cylinder liner. The piston/liner system which is to be developed comprises a light metal infiltrated graphite piston, graphite based piston rings, and an adapted cylinder liner. The cylinder liner is intended to match the employed graphite piston and piston ring for the tribological properties and with respect to the coefficient of thermal expansion (CTE). Based on the technical data of the engines to be tested, the main requirements - in terms of physical material characteristics - on the materials for pistons as well as cylinder liners have been defined. Additionally, the necessary piston and cylinder liner design of the engines has been worked out. A large number of light metal infiltrated graphite blanks in the size of the intended pistons have been produced, exhibiting properties meeting the target values for the corresponding piston applications. These samples have been characterised with respect to their physical and mechanical properties. Subsequently, pistons for engine as well as hydropulsator tests have been machined out of the blanks and successfully tested. Based on the materials properties, extensive FEA calculations both for the PDI and for the Piaggio 2stroke and 4stroke piston have been completed. These calculations have shown that the light metal infiltrated graphite is well suited for piston applications even in heavily loaded engines like the Volkswagen PDI engine. Engine tests for small 2Stroke and 4Stroke engines have shown that the developed piston material exhibits significant advantages compared with standard aluminium alloy pistons. An increase in engine output and torque as well as a decrease in fuel consumption along with a reduction of CO and soot emissions has been recorded. PDI engine tests have proven the mechanical stability of the pistons and have shown comparable properties to those with aluminium piston equipped engines. Additionally, samples for piston ring applications and a larger number of blanks for cylinder liner applications already in real size have been developed and been produced. Exceptional physical properties have been obtained by infiltration of special graphites or saw dust samples with liquid silicon. It has been shown that the pore size distribution of the new graphite materials for the infiltration with aluminium alloys is of special importance for the results of the infiltration. It has been proven that graphites with small pores lead to excellent physical properties but suffer of very poor infiltration properties. For the improvement of the unfavourable wetting behaviour of the basic graphite, different wetting agents (fluorine containing compounds) as well as electroless Nickel plating have been tested. It has been shown that both routes are well suited in order to facilitate the light metal infiltration, even using the gas pressure infiltration method. The majority of the graphite blanks have been infiltrated by the squeeze casting method. The production yield gives enough room for improvement, but the achieved physical properties are outstanding (A). Only abstract (as above) is available from the conference proceedings. For the covering abstract of the conference see ITRD E212343.
Samenvatting