Preparation of 3D orthogonal woven C–SiC composite and its characterization for thermo-mechanical properties

3D-orthogonal-woven-C–SiC composite blocks were fabricated using liquid–silicon-infiltration and were characterized for thermal and mechanical properties. Coefficient of thermal expansion (CTE) and thermal-diffusivity of the blocks were determined in the three mutually perpendicular directions. CTE was found to lie in the range −0.5 × 10−6 to 0.9 × 10−6/°C over the temperature range 25–1050 °C while thermal diffusivity was found to be in the range 37.0–7.0 mm2/s over the temperature range 25–1200 °C. The composites were subjected to sudden heating at a heat flux of 0.9 W/mm2 for 20 s and cooling by a blast of air, upto 5 times. Three point bend test of the specimens was carried out. After five thermal shocks the composites retained about 59% of the initial strength (190 MPa); after each thermal shock, the composite retained 85–90% of the previous strength. The composites showed excellent resistance to thermal shock and chemical erosion necessary for re-usable aerospace applications.