Hybrid nanocomposites: A new route towards tougher alumina ceramics

This paper describes a new class of alumina composites based on a novel hybrid microstructure design, in which multiwalled carbon nanotubes (MWNTs) and SiC nanoparticles are combined to give a new type system of ceramic nanocomposites. This design provides mutually redundant mechanisms to enhance the strength and toughness of the alumina matrix without deteriorating its intrinsic properties such as hardness. The hybrid alumina composites with different MWNT contents (0, 5, 7, and 10 vol%) and 1 vol% of SiC were fabricated by spark plasma sintering. The resulting significant improvement in mechanical properties, specially the fracture toughness, is substantiated by direct evidence for toughening mechanisms by MWNTs, observed for the first time in highly disordered MWNT/alumina composites.