Dispersion of carbon nanotubes in iron by wet processing for the preparation of iron-carbon nanotube composites

A new aspect of dispersion issue regarding carbon nanotubes (CNTs) into the iron matrix was studied. As-received unpurified CNTs were purified at 450-550 degrees C followed by treatment with H2O2 at different conditions. The effect of time and temperature on the oxidation and purification of CNTs was investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Afterward a wet chemical process was developed to achieve a uniform dispersion of CNTs in submicron Fe powder (<= 2 mu m) as matrix. Purified CNTs were functionalized and dispersed in ethanol by polyethylenimine (PEI). It was deduced that use of the functionalized CNTs and PEI prevented reagglomeration of CNTs in solution which would allow good dispersion and stable CNT solution. A sub-micron size Fe powder synthesized by a mechanical milling and special sorting technique was also added to this stable CNT suspension to achieve Fe-CNT composites. Uniform dispersion of CNTs into the submicron Fe matrix was confirmed by field emission scanning electron microscopy (FESEM). (C) 2014 Elsevier B.V. All rights reserved.