PROCESSING OF OXIDE/OXIDE COMPOSITES FOR GAS TURBINE APPLICATIONS BASED ON BRAIDING TECHNIQUE (OXITEX ™)

摘要

New concepts for aerospace applications such as gas turbine aero-engines require advanced lightweight structural materials with superior high temperature environmental stability in order to increase operation efficiency and to reduce CO_2 emission. Beside others, oxide/oxide CMC can fulfil these demands for high performance turbines due to their inherent oxidation resistance, good thermo-mechanical properties at elevated temperatures and low density. For some decades now EADS Innovation Works uses the filament winding technique and PIP process (Polymer Infiltration Pyrolysis) for the manufacture of a specific oxide/oxide CMC termed UMOX™. Continuous oxide based Nextel™ fibers (3M™, USA) such as Nextel™610 alumina fibers are impregnated with pre-ceramic slurries via filament winding and further processed to a green body following by high temperature treatment where the matrix is converted to a ceramic state. Besides specific advantages such as excellent reproducibility the drawback of this process is based on high manufacturing costs due to long process times and pyrolysis steps. To overcome this disadvantage and due to the strong demand for high performance materials a new process for the fabrication of an oxide/oxide CMC type, termed OXITEX™, using the tailored circular braiding technique was successfully investigated and developed. The development approach and exemplary CMC material characteristics are presented. The paper concludes with the next steps together with the demonstration of a preliminary combustor liner structure for gas turbine engine application since part of the presented work was performed within the German BMBF HiPOC program (High Performance Oxide Ceramics). The main focus of the project is the development of oxide/oxide CMC materials and structures for the envisaged use in gas turbine engine applications.