Novel production route for SiC/SiC ceramic-matrix composites using sandwich prepreg sheets

We report a novel route to produce high quality SiC/SiC ceramic-matrix composites. A SiC slurry with binders was prepared by mixing SiC nano- and submicron-powders with sintering additives in isopropanol, which was then used to impregnate SiC fibers and form green sheets without fibers. The prepreg sheets were placed between two SiC green sheets to form a sandwich structure and warm-pressed at 100 degrees C under low pressure. The debinding was performed at 800 degrees C for 1 h, and the densification of the SiC matrix was conducted by pressuresintering at 1850 degrees C for 1.5 h under 20 MPa. Sandwich prepreg sheets showed a more controllable sheet thickness and smoother fiber bundles, compared to prepreg sheets prepared by hand that caused broken fibers and irregular thickness. The SiC/SiC ceramic-matrix composites using sandwich prepreg sheets exhibited excellent bending strength and tensile properties.