Fabrication and Mechanical Properties of Reaction-Bonded Carbon Fiber/Si/SiC Composites.

Abstract

Two types of low-density carbon/carbon preforms which had different fiber volume fractions and fiber orientations, i.e., a carbon woven fabric (≈55vol%)/carbon and a chopped carbon fiber (≈40vol%)/carbon composites, were reaction-bonded with a silicon melt at 1750°C in vacuum to fabricate dense carbon fiber/Si/SiC composites. The reaction-bonding process increased the density to -2.1g/cm3 from 1.6 and 1.15g/cm3 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 2.06g/cm3 exhibited a -120MPa ultimate strength and a -80MPa proportional limit in bending test.