The effect of carbon nanotubes on the sintering behaviour of ceramics
Researcher: Ben Milsom
Supervisors: Professor Michael Reece (Queen Mary University of London) and Professor Bill Lee (Materials)
Funding: Centre for Advanced Structural Ceramics
Carbon nanotubes (CNTs) have outstanding chemical inertness, stability at high temperatures, thermal, electrical and mechanical properties with a decreasing cost trend, which makes them a potential reinforcement for ceramic matrices for room and high temperature structural applications. CNTs have been shown to be stable at temperatures as high as 2000-2430°C in an argon atmosphere or under vacuum. The addition of CNTs to ceramics can significantly increase their electrical and thermal conductivities, and there are some reports that they can also increase fracture toughness. The role of CNTs in the sintering of ceramics is not clear in the literature, possibly because of differences in the dispersion and mixing of the CNTs, their degradation during processing, and the densification of the composites. Preliminary results at QMUL, involving rapid sintering by Spark Plasma Sintering (SPS), have shown that CNTs increase the sinterability of the composites while significantly retarding grain growth. The rate of grain growth with time is linear, not parabolic, as is the case with monolithic and composite ceramics. The proposed project will involve a systematic study of the effect of CNTs of the sintering and grain growth behaviours and kinetics of different ceramics (alumina, boron carbide and silicon carbide) prepared by SPS. The objective of the project is to understand the effect of CNTs on sintering, explain the above mentioned observations and elucidate any new mechanisms that may exist.