A carbon nanotube/alumina network structure for fabricating alumina matrix composites

A network structure of carbon nanotubes (CNTs) and nickel/alumina (CNT(Ni)-Al2O3) composite particles was developed, which involved producing a Ni(OH)(2)/Al precursor, followed by calcination in air and reduction in hydrogen to yield a Ni/Al2O3 catalyst with a network structure, which was used to synthesize nanotubes by chemical vapor deposition. The CNT(Ni)-Al2O3 hybrid was then employed to produce alumina matrix composites by spark plasma sintering of the CNT(Ni)-Al2O3 composite powder. Microstructure and mechanical properties of the composites were characterized. The results showed that the CNTs dispersed homogenously and bonded strongly with the alumina matrix and the composites showed a 67% increase in fracture toughness and 17.5% increase in hardness compared to monolithic alumina. The improvement of the fracture toughness and hardness was attributed to the network structure of CNT(Ni)-Al2O3, which ensured homogenously dispersed CNTs in the matrix and tight interfacial bonding between CNTs and alumina matrix, and thus led to a good stress transfer between the nanotube and alumina matrix. (C) 2008 Elsevier B.V. All rights reserved.