Strength of metal impregnated C/C under tensile cyclic loading

An experimental investigation is conducted on the tensile cyclic behavior of metal impregnated composites based on a preformed yarn method such as Cu-C/C and Si-C/C together with C/C. Specimens are loaded cyclically in tension and tension. Their S-N curves and the fatigue strength of about 0.8UTS at around N = 10⁴ were obtained. Macroscopic and microscopic characteristics are discussed to yield the cyclic failure mechanism as follows. In a low cycle region, the decrease of shear resistance caused by wear at the fiber/matrix interface increases the probability of fiber break, while after about 10⁴ cycles the smoother interface and longer debonding area suppress the decrease of shear resistance. Thus, the probability of fiber break does not increase.