Super-hard boron carbide/silicon carbide composites by reactive infiltration

Metal-ceramic composites based on B4C and SiC phases were obtain by infiltration of porous boron carbide preforms, enriched with free carbon, by silicon melt. Sugar as a precursor for free carbon was used. Porous boron carbide preforms with 35% porosity were infiltrated with sugar solution (100 gram sugar in 100 ml water). The sugar pyrolyse was performed at 500°C under argon. After the pyrolysis the preforms with 12 %wt. of free carbon were infiltrated with silicon at 1480°C under vacuum of 10^-4 torr. The resulted composites show homogeneous structure consisting of interconnected boron carbide and silicon carbide particles with 10%vol. of residual silicon. The hardness of the composites is about 2700HV and the elastic modulus is about 350GPa.