Mini-composites C/SiC tensile strength at elevated temperature in vacuum

As the regularity of strength of C/SiC composites with elevating temperature is obscure, the mini-composite C/SiC is applied in present investigation for this purpose. The C/SiC mini-composite specimen is fabricated with T300PAN carbon fiber, its work section contains one fiber yam tow and the other part six tows. The tensile experiments of mini-composites are carried out in vacuum around 10(-5) torr from room temperature to 1700 degrees C. Tensile strength of mini-composites in the range around 900-1300 degrees C is higher than that at other temperature. In strong interface bonding condition, fibers' strength decrement of mini-composite mainly attributes to the internal thermo-stress induced by expansion coefficient mismatch between carbon fiber and SiC matrix, and the stress concentration generated by SiC matrix crack. The stress concentration coefficient is 3.59 by matrix crack for C/SiC mini-composites. At 1300 degrees C, mini-composite's strength Weibull modulus is 3.65. In the fracture surface of mini-composite, the fiber fracture mirror has not been found very clear.