Abstract
Si_3N_4-matrix SiC whisker reinforced composites (CMC) have higher fracture toughness if the size and the fraction of whisker or matrix powder, are appropriate. Though the condition is not apparent, it is concerned with the mechanical properties of grain boundary. In this study, the high temperature internal frictions of CMC and Si_3N_4 were measured by an inverted torsion pendulum Strength tests and fracture surface observation were also conducted. The relationship between higher toughness of CMC and these experimental data was investigated.
