Investigation of effect of siliconization conditions on mechanical properties of 3D-stitched C–SiC composites

Three-directional carbon fiber reinforced silicon carbide composites were fabricated using liquid silicon infiltration. Siliconization was carried out at nine different conditions to achieve best mechanical properties. Flexural strength, tensile strength and fracture toughness of the composites were determined at each condition. Flexural and tensile strengths increase with siliconization time and temperature. At 1650 °C and 120 min mechanical properties are found to be the best. Arithmetic mean average flexural and tensile strength values were found to be 177 and 90 MPa, respectively. The flexural strength data were also analyzed by the Weibull modulus approach; it was found to be the highest (13.28) for composites siliconized at 1550 °C, 120 min and the least (7.01) at 1450 °C, 10 min. The fracture toughness of the composite blocks was found be in the range 5 – 6   MPa m . The strength data were also correlated with chemical composition of the composites and the microstructure obtained during processing.