Net Shape Manufacturing of Fabric Reinforced Oxide/Oxide Components via Resin Transfer Molding and Pyrolysis

CMC materials on the basis of oxide fibers and oxide matrices offer inherent oxidation stability and chemical resistance and therefore can be used for long term applications at high temperatures. For this materials one of the most interesting field of application are aircraft turbine engines, e.g. for thin-walled structures of hot gas liners or for heat shields in the combustion chamber. The DLR developed a modified process for the manufacturing of Oxide/Oxide-CMC on the basis of the liquid polymer infiltration (LPI). Hereby, dry preforms made of fiber fabrics were pressure infiltrated with polysiloxane precursors via resin transfer molding (RTM) and pyrolised. To demonstrate the process` potential for the manufacture of large complex CMC structures, an exemplary intake ramp for a propulsion system was developed. The intake ramp was made in a near net shape technique by the manufacturing of seven thin-walled, tubular profiles which were nondetachably assembled during an in situ joining process. The effort for the final machining with diamond coated tools could therefore be reduced to the interface regions. With this technique a thin-walled, complex structure with outer dimensions of 265 mm x 110 mm x 35 mm and a low mass of only 0.4 kg could be realized. In this paper, the material properties and the construction and manufacturing of the intake ramp is presented