Silicon/silicon carbide composites fabricated by infiltration of a siliconmelt into charcoal

Dense Si/SiC composites were fabricated via a conventional reaction-bonding process, using oak charcoal that exhibited a honeycomb structure. The sili con melt was infiltrated into the porous oak charcoal (density of similar t o 0.6 g/cm(3)) while the sample was heated to 1700 degrees C under vacuum ( 10(-3) torr (similar to 0.133 Pa)), which resulted in irt situ silicon-fibe r/SiC composites. The reaction product had an average density of 2.8 g/cm(3 ) and showed three-point flexural strengths of 330 MPa at room temperature and 280 MPa at 1300 degrees C. Good oxidation resistance also was observed at temperatures up to 1300 degrees C in flowing air. This process provided excellent shape-making capability, because the charcoal that was used as a preform was readily machinable.