Nanotube-containing composite bodies, and methods for making same

A composite material featuring carbon nanotubes reinforcing a matrix featuring metal or silicon carbide, or both. Such composites can be produced using a molten silicon metal infiltration technique, for example, a siliconizing or a reaction-bonding process. Here, the carbon nanotubes are prevented from chemically reacting with the silicon infiltrant by an interfacial coating disposed between the carbon nanotubes and the infiltrant. Preferably, the coating is free carbon or a carbonaceous precursor material added during preform processing, or after. The reaction-bonding system is designed such that the molten infiltrant of silicon metal or silicon alloy reacts with at least some of the interfacial carbon layer to form in-situ silicon carbide, and that the formed SiC is sufficiently dense that it effectively seals off the underlying carbon nanotube from exposure to additional molten infiltrant. A reaction-bonded composite body containing even a small percentage of carbon nanotubes possessed a significant increase in electrical conductivity as compared to a reaction-bonded composite not containing such nanotubes, reflecting the high electrical conductivity of the nanotubes.