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

Two types of low-density carbon/carbon preforms which had different fiber v olume fractions and fiber orientations, i.e., a carbon woven fabric (approx imate to 55 vol%)/carbon and a chopped carbon fiber (approximate to 40 vol% ) /carbon composites, were reaction-bonded with a silicon melt at 1750 degr ees C in vacuum to fabricate dense carbon fiber/Si/SiC composites. The reac tion-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, respectiv ely. All of the composites fractured with extensive fiber pullout. The high er 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) exhib ited a similar to 120 MPa ultimate strength and a similar to 80 MPa proport ional limit in bending test.