Influence of short carbon fiber content on mechanical and dielectric properties of C_fiber/Si₃N₄ composites

C_fiber/Si₃N₄ composites were prepared by hot-pressed sintering using α-Si₃N₄ powders, short carbon fibers and sintering additives as starting materials. The mechanical and dielectric properties of these composites were studied. When the short carbon fiber content of the composites increases from 0 to 1 wt.%, the fracture toughness increases from 3.456 to 4.203 MPa m^1/2, and both the real and imaginary part of permittivity increase greatly over the frequency range 8.2-12.4 GHz. These effects were due to the anisotropy of short carbon fibers.