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

•A sub-micron size iron powder by a novel sorting technique was obtained.•The effect of time and temperature of oxidation on the amount of functional group and purification of CNTs was investigated by thermal analysis.•The purification, cutting and using PEI as surfactant lead to a stable ink-like CNT solution.•FESEM results show good dispersion of CNTs with lengths of less than 100 nm in the Fe matrix.

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 °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 μm) 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).

Graphical abstractIncreasing the oxidation time leads to increase of intensity of peaks and temperature of the exothermic peaks moves towards lower temperaturesCNT clusters and homogenous dispersion of CNTs in iron by wet processingFigure optionsDownload full-size imageDownload as PowerPoint slide