Effect of CNT distribution on tribological behavior of alumina-CNT composites

Alumina-carbon nanotube (CNT) composites with a different volume fraction of CNTs were fabricated by two different processing methods to investigate the effect of the distribution of CNT in the ceramic matrix on the tribological behavior. Alumina-CNT composites with CNT content up to 12 wt.% were fabricated by tape casting, followed by lamination and hot pressing. For the comparison, composites with the same composition were prepared by hot pressing. The friction and wear behaviors of the CNT reinforced composites were investigated using a ball-on-reciprocating wear tester under an unlubricated condition at room temperature. The wear rate of hot-pressed samples decreased with increasing up to 4 wt.%, but increased with further addition of CNT. The wear rate of the tape casted composites decreased steadily with increasing CNT addition up to 12 wt.%. Density and mechanical properties depending on CNT addition were measured. SEM was employed to observe worn and unworn surface. All the results demonstrated that tape casting process significantly improved the uniform distribution of CNT in the alumina, resulting in enhanced wear resistance of composites.