Well-Dispersed Carbon Nanotubes for Greatly Enhanced Mechanical Properties of Alumina-Based Composites

Abstract

Multi-wall carbon nanotubes (MWCNTs) reinforced Al2O3 composites (MWCNTs/Al2O3) have been prepared by a hot-pressing method, and the mechanical properties of the composites are investigated. Compared with the pure alumina, when adding 1.5 wt.% MWCNTs into the Al2O3 matrix, the composites have much higher flexure strength (403.6 MPa) and fracture toughness (4.21 MPa·m1/2), which shows a simultaneous increase of 38% in flexure strength and 35% in fracture toughness. The microstructural observations of MWCNTs/Al2O3 composites show that MWCNTs are homogeneously dispersed and embedded strongly in the alumina matrix due to the electrostatic interaction between MWCNTs and Al2O3, resulting in great improvement of flexure strength and fracture toughness. The reinforcement mechanism of the composites is mainly the pullout of MWCNTs from the matrix, MWCNTs bridging and crack deflection.