In situ characterization of tensile-bending load bearing ability of multi-walled carbon nanotubes in alumina-based nanocomposites

The tensile-bending load bearing ability (LBA) of individual multi-walled carbon nanotubes (MWCNTs) embedded in α-alumina ceramic was examined using a unique, in situ method, in which a nano-manipulator and an electron microscope were simultaneously used. Considerably improved LBA compared to near-perfect, straight, arc discharge-grown MWCNTs in vacuum was observed even for MWCNTs under large deflections, which is attributed to the strong inter-wall shear resistance engineered in MWCNT structure due to the radial compressive stress applied from the surrounding alumina ceramic. Crystallinity and exceptional flexibility of MWCNTs after incorporation into the alumina by using spark plasma sintering were shown to remain unchanged. Our results confirm a mutual strengthening phenomenon in MWCNT/alumina nanocomposites and that even MWCNTs with large deflections are an exceptional reinforcement for alumina-based nanocomposites, though they require uniform dispersion and intimate interfaces.