Short Fibre reinforced CMC
Oxide-CMC are preferred for high temperature applications due to their mechanical behaviour like bending strength, thermal shock-, corrosions- and temperature resistance which are commonly reinforced with wovens or braidings. These textiles are expensive and time-consuming to
manufacture. Their high properties, especially the bending strength, are not always necessary concerning the applications, e.g. inhousing of high temperature cameras, furnace insulation or product carriers. Within a research project in cooperation with an O-CMC manufacturer funded by the German government, the purpose was to develop a ceramic short fibre wet-laid nonwoven for ceramic slurry infiltration.
As a substitute for wovens and braidings in O-CMCs, a wetlaid is built of Al2O3 fibres ranging from 625 mm in length. The fibres are pulped in water for the wet forming process. The bending strength at room temperature amounts to 20% of conventional manufactured O-CMCs. To increase the strength a hybrid wet-laid is built using rovings in the bottom layer covered with chopped fibres and achieves 60% strength with a quarter of the fibre volume content. The target of achieving a short fibre reinforced O-CMC is obtained, and shows properties for low-middle bending strength applications at up to 40% reduced costs.