ELECTRICAL, MECHANICAL, AND THERMAL PROPERTIES OF MULTIWALLED CARBON NANOTUBE REINFORCED ALUMINA COMPOSITES

The outstanding electrical, mechanical. and thermal properties of carbon nanotube (CNT) have prompted the research for development of advanced engineering composites with improved properties. It is based on the notion that by combining CNT with ceramics, some of the attractive properties of CNT may be transferred to the resulting composites. Most of the studies were focused on improving the fracture toughness of alumina by using CNT. In this work, we have investigated multi functional properties of multiwalled carbon nanotube (MWNT)/alumina composites to make the most of the exceptional characteristic of MWNT in the resulting composite. Results have shown that the low fractions of MWNT can be used successfully to convert electrically insulating alumina into electrically conducting composites through percolating network of MWNT at the grain boundaries. In case of mechanical properties, the fiber toughening by MWNT was found main mechanism for fracture toughness improvement. The thermal conductivity and thermal diffusivity of the composites decrease with MWNT contents. suggests that interfacial thermal barrier between MWNT and alumina play a key role in determining these properties. Low volume fraction of MWNT call be used successfully to concurrently improve electrical and mechanical properties of alumina without deteriorating other intrinsic properties. This kind of multi functional alumina composites with improved electrical and mechanical properties but with reduced thermal properties call be employed for a wide range of potential applications as structural and functional ceramics.