▎ 摘　　要

In this study, Al2O3-based nanocomposites reinforced with multiple nano-materials, namely zirconia (ZrO2), graphene (GN) and carbon nanotubes (CNTs) were processed to investigate the synergistic effect of the multimaterials on the microstructural evolution, mechanical properties and tribological behaviour, including the mechanism of wear. The monolithic Al2O3 and Al2O3-based nanocomposites reinforced with 10wt%ZrO2, 0.5wt %GN and 2wt%CNTs were prepared using a colloidal mixing and sintered at a temperature of 1600 degrees C. Benchmarked against the monolithic Al2O3, a single addition of 10wt%ZrO2 gave about 25% decrease in matrix grain size, whilst a remarkable reduction in both the matrix and ZrO2 grains, up to 80% and 46% respectively, was achieved with the multiple combination of ZrO2, GN and CNTs. This was due to the effective parallel pinning action of the matrix grains by the homogeneously dispersed multi-materials to the monolithic Al2O3. Vickers hardness also increased to 48% with combined additions of GN and CNTs, as opposed to the 25% decrease with a single addition of ZrO2 relative to the monolithic Al2O3 material, which was attributed to the refined grain structures and effective load transfer capabilities of the combined multi-phase materials. In addition, the fabricated nanocomposite incorporated with only 10wt%ZrO2 resulted in 88% decrease in wear rate, whilst the multiple additions of GN and CNTs exhibited better wear resistance, with up to 93% wear rate reduction as compared to the monolithic Al2O3. The improved wear resistance of the nanocomposites with the multiple additions of GN and CNTs was due to the micro-crack bridging and restriction to intergranular fracture that leads to pull-out of the matrix grains under sliding wear. Also, the combined crack pinning by the finely dispersed ZrO2 particles, and bridging action of the GN and CNTs suggest a synergistic response of these multi-materials to the wear performance of the fabricated multi-material nanocomposites.