Influence of an initial hot-press processing step on the mechanical properties of 3D-C/SiC composites fabricated via PIP

Hot press is firstly used before infiltration and pyrolysis cycles to enhance the densities and the mechanical properties of three-dimensional-braided carbon fibers reinforced SiC composites (3D-braided C/SiC) fabricated via preceramic infiltration-pyrolysis (PIP) process. The influences of temperature, pressure, temperature at which the pressure should be applied, holding time and introduction of inert fillers during the hot-pressing process are especially studied. The results show that the hot-press step used before the PIP cycles is positive to the mechanical properties of the materials. The 1873 K, 1 MPa, 5-min hot-pressing parameters give good properties to the materials. It is beneficial to the properties that hot press is applied after PCS is pyrolyzed to β-SiC completely. Conversely, the introduction of inert filler SiC powders to enhance the properties of the materials is not effective under the above conditions.