Preparation of porous alumina–carbon nanotube composites via direct growth of carbon nanotubes

A simple approach is reported for the in situ growth of carbon nanotube-containing porous alumina structures by a thermal pyrolysis method. The composite was created by direct on-site growth of carbon nanotubes inside the porous alumina matrix, after introducing both a catalyst (Ni(NO3)2) and a carbon source (camphor) into the cavities of the large matrix brick. Pyrolysis was carried out when the pre-treated brick was heated in a furnace at 850 °C under a H2–Ar atmosphere. The resulting multi-walled carbon nanotubes with average diameters of 30–70 nm and lengths up to several micrometers are dispersed uniformly at each section of the alumina matrix. An improvement in the compression strength of the composites has been obtained, due to the inclusion of carbon nanotubes.