Spray winding, a novel one-step spray-technology to perform CMCs from preceramic polymers

A novel spray-technology to perform CMC tubes has been developed in order to establish an one-step process which enables shorter process times along with the saving of costs. The manufacturing route combines the textile fibre technique with both matrix polymer spraying and IR heated curing/pyrolysis which transfers the preceramic polymers into an inorganic amorphous SiOC matrix. plied metalorganic polymer as a commercial polysiloxane precursors which can be easily handled in air. The use of an organic solvent and WC-filler particles enables a low viscous suspension. Carbon fibres were wound onto a rotating tapered mandrel and simultaneously spray-coated with the polymer suspension, i.e. fibre winding and matrix spraying occurred at the same time to build up the CMC tube layer by layer. A heatable two flux nozzle is positioned perpendicular over the rotating mandrel and coats the surface continuously. An ellipsoid IR-mirror furnace which cures and pyrolyses the matrix (up to about 900 °C) was in 180° orientation displaced, focusing its radiation onto the surface. Rotation and traverse speed of the mandrel were computer controlled to facilitate a variability in fibre architecture. In a circular ring-test small winding angles leads to a maximum strength of 45 MPa. Because the shrinkage of the matrix polymer occur at a free surface only very limited strain hindrance arises.