Carbon nanotubes reinforced alumina matrix nanocomposites for conductive ceramics by additive manufacturing

Alumina has been extensively used due to its high toughness and hardness, low bulk density, and thermal stability without interaction with the matrix at high temperature. However, the non-conductivity at room temperature narrows its broader applications. Carbon nanotube (CNT) is a suitable candidate to adjust the electrical property of alumina matrix composites due to its high electrical conductivity. By using material extrusion 3D printing (ME3DP), we fabricated 3D CNT/alumina green bodies using inks with controlled rheological properties for high printability. The printed green bodies with CNT loading from 3 wt% to 10 wt% were thermally treated to remove binders and sinter the 3D parts at temperatures from 900 to 1400 °C. The sintered samples showed a good dispersion of CNT in the alumina matrix and improved electrical conductivity. The electrical conductivity of the composites measured up to 10-1 S/m at 7 wt.% CNT loading, compared to the electrical conductivity of 10-13 S/m of pure alumina.