A new structure for multi-walled carbon nanotubes reinforced alumina nanocomposite with high strength and toughness

Multi-walled carbon nanotubes (MWCNTs)/Al2O3 massive composites with a new carbon nanotubes (CNTs) dispersion structure have been prepared by hot-pressing. Microstructure observations of the nanocomposite show that some CNTs site along alumina grains boundary and others embed into the alumina grains to knit neighboring alumina grains together just like “pin” structure, which would contribute to toughness increase and bending strength increase respectively. The reinforcement mechanism is mainly CNT pullout and crack bridging being observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). For 3 vol.% CNTs/Al2O3 composite, a fracture toughness increase of 79% and bending strength increase of 13%, comparing with that of pure nanocrystalline alumina, can be achieved.