Properties of alumina matrix composites reinforced with SiC whisker and carbon nanotubes

Abstract The microstructure and mechanical properties of Al 2 O 3 containing 0, 0.1, 0.5 or 1.0 wt% multi-walled carbon nanotubes (MWCNTs) were examined with/without the addition of 25 wt% SiC whisker (SiCw) for cutting tool applications. Eight types of composites with different compositions and a density >99% could be manufactured by optimizing the hot-pressing conditions. The addition of MWCNTs had negligible effects on the mechanical properties of the resulting Al 2 O 3 –MWCNTs composites due to agglomeration and the retardation of sintering. On the other hand, the incorporation of SiCw to Al 2 O 3 enhanced the mechanical properties significantly, which enabled the cutting of Inconel 718 super-alloy. Both K 1C and the flexural strength of Al 2 O 3 –SiCw–MWCNTs were improved by >60% compared to those of the Al 2 O 3 –MWCNTs composites. Moreover, it was proposed that the MWCNTs in the Al 2 O 3 –SiCw reduced the wear of the cutting tool by lubrication when the high composite density was ensured.