Reinforcement of Al2O3–MgO composite materials by multiwalled carbon nanotubes

Abstract

Composite materials based on the Al₂O₃–MgO system reinforced with multiwalled carbon nanotubes (MWCNTs) were fabricated by vacuum sintering and hot pressing. The ceramic matrices were represented by corundum Al₂O₃ ceramic with the addition of 0.25 wt % MgO and magnesium aluminate spinel MgAl₂O₄. The prepared composites based on corundum and magnesium aluminate spinel containing MWCNTs were investigated by optical microscopy and scanning electron microscopy, and their microhardness and fracture toughness were studied. The samples are a densely sintered matrix with the average crystallite size of 3–5 μm with MWCNTs distributed uniformly on grain boundaries forming a reticular carcass. The samples of the Al₂O₃–MgO composite with 8 vol % MWCNTs demonstrated the flexural strength and fracture toughness two times higher as compared to the initial ceramic material (Al₂O₃ + 0.25% MgO).