Pressureless Sintering of Alumina Carbon Nanotubes Composites in Air Atmosphere Furnace and Their Mechanical Properties

概要

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Since Iijima first reported carbon nanotubes in 1991, a lot of researchers have conducted study on their mechanical and electrical properties. Recently, multi-wall and single wall nanotubes have been used as reinforcing material for composites in matrix of aluminium, SiC, epoxy and alumina. In this paper, alumina matrix composites containing 0.1 to 2 weight percent of multi-wall carbon nanotubes (MWNT) were successfully fabricated by pressureless sintering in air atmosphere. The composites sintered to nearly full density. Hardness, fracture toughness and bending strength were measured using Vickers indention method and the three-point-bending test. The hardness of the composite decreased with increasing weight content of the MWNT. The fracture toughness does not change much with the amount of MWNT, while the bending strength increased with the added amount of CNTs. Microstructure characterization, performed by SEM, showed that the tight bonding between CNTs and alumina matrix, the pullouts of CNTs from matrix and the thermal expansion mismatch are possible mechanisms leading to the improvement of the mechanical properties. The samples sintered by SPS (spark plasma sintering) were employed for comparison.
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