Effects of microstructure defects on the internal friction of C/SiC composites

The internal friction of C/SiC composites was studied by forced vibration at the frequency and amplitude modes, and the effects of microstructural defects on the internal friction of C/SiC composites were investigated systematically and the internal friction mechanism was also discussed. Test results indicated that the microstructure defects in C/SiC samples improved the internal friction and had greater effects on the internal friction tested at low frequency and high amplitude. The slip friction of weak interphase was the main internal friction mechanism for C/SiC samples with interphase damage, and the internal friction increased slowly with the porosity. As the interphase was corroded completely, the pores in C/SiC composites became the main factor controlling the internal friction, and the internal friction increased rapidly with the porosity.