Fabrication and mechanical properties of reaction-bonded carbon fiber/Si/SiC composites

Two types of low-density carbon/carbon preforms which had different fiber volume fractions and fiber orientations, i.e., a carbon woven fabric (approximate to 55 vol%)/carbon and a chopped carbon fiber (approximate to 40 vol%) /carbon composites, were reaction-bonded with a silicon melt at 1750 degrees C in vacuum to fabricate dense carbon fiber/Si/SiC composites. The reaction-bonding process increased the density to similar to 2.1 g/cm(3) from 1.6 and 1.15 g/cm(3) for carbon woven and chopped carbon preforms, respectively. All of the composites fractured with extensive fiber pullout. The higher the density, the higher the stiffness and proportional limit stress. The carbon woven fabric/Si/SiC composites with a density of 2.06 g/cm(3) exhibited a similar to 120 MPa ultimate strength and a similar to 80 MPa proportional limit in bending test.