Alumina/carbon nanotube (CNT) composites with different CNT contents were fabricated by hot-pressing to investigate the effect of CNT additions on the microstructure and mechanical properties of the composites. Alumina/CNT powders were obtained by forming the CNTs with the aid of catalyst particles supported on the alumina particles. The CNT contents were varied from 0 to 12.5 wt.% by changing the content of the iron nitrate catalyst precursor. The relative densities and the matrix grain size decreased with increasing CNT content. Hardness reached a maximum with about 4 wt.% added CNT. The effect of CNT additions on microhardness was explained by the matrix microstructure and reinforcement effect of CNT.

Keywords: Carbon nanotube (CNT), Alumina/CNT composite, Microstructure