A new automotive application for ceramic matrix composites (CMC): C/C-SiC based piston rings for internal combustion engines (IC-engine)

Abstract

Alternative energy and the transition away from fossil fuels is one of the core subjects of current politics. In the automotive industry the internal combustion engine, however, remains the most commonly used power unit. In terms of improving its environmental compatibility, the current research goal is to increase its efficiency and service life while maintaining or even reducing the fuel consumption. The DLR develops a ceramic fiber-reinforced piston ring, which should contribute to fuel savings and reduced piston wear. In order to investigate fundamental questions of feasibility and functionality, piston ring prototypes made of C/C-SiC (carbon fiber reinforced silicon carbide) were developed in cooperation with the DLR Institute of Structures and Design and DLR Institute of Vehicle Concepts. For a ceramic piston ring the mounting is one of the most restricting requirements, as the material is usually not flexible and fiber reinforcement has to be carefully adjusted in order to provide elastic behavior. Within the project, variants of C/C-SiC with different preforming technology were developed. Weaving-, winding- and tailored fiber placement-technologies were used for preform manufacturing. The mechanical examination of the samples was carried out according to ASTM C1323 - 16 for ceramic C-rings and the results were promising. In addition, the work provides further insights into the expected running behavior of the ceramic piston rings and how economic production can be achieved. Further research now aims at examining the effects on the energy consumption and service life when utilized in IC-engines.