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·m^1/2), 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.