Electrical conductivity and microwave absorption of shortened multi-walled carbon nanotube/alumina ceramic composites

Multi-walled carbon nanotubes (MWCNTs) snipped by the acidification process were fabricated into alumina (Al2O3) matrices via hydrothermal crystallization and hot-pressing techniques for achieving MWCNT/Al2O3 composites. The electrical conductivity and complex permittivity of the as-fabricated composites were investigated in the range of 8.2–12.4 GHz, and the corresponding microwave reflection loss was evaluated. Compared to the pristine MWCNT/Al2O3 composites, the percolation threshold of electrical conductivity was observed to increase from the range of 0.094–2.5 wt% to 3.89 wt%, mainly owing to the decrease of MWCNT aggregations based on the shortened tubes. The resulting shortened MWCNTs/Al2O3 were found to demonstrate strong microwave absorption in the investigated region.