Abstract
Carbon nanotubes (CNTs) offer a new class of material as reinforcements for the development of ceramic composites, due to their intrinsic mechanical and other functional properties. In previous studies, pressure-assisted sintering methods such as spark plasma sintering (SPS) and hot pressing (HP) are the two techniques that have been commonly employed to prepare CNT/ceramic composites. In this research, in order to evaluate the effects of the sintering method on the mechanical properties and microstructures of the composites, alumina ceramics reinforced with multi-walled CNTs (MWCNTs) were prepared by pressureless sintering and SPS. Resultant composites containing 1.9 vol.% MWCNTs prepared by the pressureless sintering and SPS had relative density as high as 97% and 99%, respectively. Fracture toughness of the composites prepared by the pressureless sintering was almost the same as that obtained for the composites prepared by SPS. Scanning electron microscope observations indicated that the MWCNTs, rather than pulling out from the alumina matrix, failed by clean break. For the design of tougher ceramics with MWCNTs, appropriate modification of fiber/matrix interface will be one of important factors.
