Toughened carbon nanotube-iron-mullite composites prepared by spark plasma sintering

Abstract

Carbon nanotube-iron mullite nanocomposite powders were prepared by a direct method involing a reduction in H2-CH4 and without any mechanical mixing step. The carbon nanotubes are mostly double-andfew-walled (3-6walls). Some carbon nanofibers are also observed. The materials were consolidated by spark plasmas intering. Their electrical conductivity is 2.4S/cm where as pure mullite is insulating. There is no increase in fracture strength, but the SENB toughness is twice than the one for unreinforced mullite(3.3vs.1.6 MPam½). The mechanisms of carbon nanotube bundle pull out and large-scale crack-bridging have been evidenced.