Manufacture and Characterisation of OXIPOL Based on Different Oxide Fibres

Within the scope of the German funded project HIPOC (High Performance Oxide Ceramics) oxide/oxide ceramic matrix composites (CMC) are further developed at DLR. These so-called OXIPOL (Oxide CMC based on Polymers) materials are investigated for the use in high thermo-mechanically loaded components in jet engine. OXIPOL materials are manufactured via polymer infiltration and pyrolysis (PIP). Hereby dry fabrics made of oxide fibres are infiltrated with powdery polysiloxane precursors via warm pressing and pyrolised. The composites are densified in up to four subsequent cycles of polymer infiltration and pyrolysis, leading to open porosities below 10%. To obtain typical CMC properties like damage tolerance and thermal shock resistance, a weak fibre matrix bonding based on fugitive coating is used. In this work, different fibres composed of alumina, alumina silicate or mullite were investigated. Additionally the fibre coating process was varied. The manufacturing process and the mechanical properties before and after exposure at 1200°C are described