Improving the properties of SiC/SiC CMC manufactured by LSI process and development of three-dimensional components

Kurzfassung

Increasing performance and efficiency of aero engines is mandatory for more environmentally friendly air transport. Rising temperatures, especially for combustion section and turbine structures, as well as lower weight of the components are key requirements for new materials. Together with adapted environmental coating systems and cooling features ceramic composites are good candidates for aircraft applications. They are capable of withstanding high temperatures in an aggressive environment while the density is 2/3 lower than conventional nickel-based alloys. Liquid silicon infiltration process (LSI) for the manufacture of silicon carbide fiber reinforced silicon carbide composites (SiC/SiC CMC) has recently been optimized. By using a novel phenolic resin, the remaining unconverted carbon in the matrix could be eliminated and the silicon proportion was reduced by ~60 %. This resulted in a higher Young’s modulus and improved proportional limit stress. Furthermore, our Institute of Structure and Design is investigating turbine vanes made from SiC/SiC material together with several other DLR institutes in DLR’s project 3DCeraTurb. One goal of 3DCeraTurb is to design and manufacture ceramic stator guide vanes for a high-pressure turbine, to experimentally investigate the blade performance in a wind tunnel and to evaluate performance, damage and lifetime for the later application in an aircraft engine. The focus at our institute is the enhancement of the manufacturing process from plate dimensions to more complex three-dimensional components.