Internal friction and dynamic modulus of three-dimensional silicon carbide-matrix composites

The internal friction and dynamic modulus of 3D C/SiC and SiC/SiC composites were investigated by means of forced vibration at elevated temperatures from room temperature to 600 °C, and the relationship between the microstructural defects in the composites and the internal friction mechanism was also discussed. It was found that the microstructural defects, which are produced by the mismatch of the coefficient of thermal expansion (CTE) between the fiber and matrix, have an important effect on the internal friction behavior and dynamic modulus of 3D C/SiC and SiC/SiC composites. C/SiC composites have a higher internal friction and lower dynamic modulus than SiC/SiC composites in the same testing conditions because of the damage.