Microstructure and properties of carbon nanotube/zirconia composite

Sintering and hot pressing have been used for preparation of monolithic ZrO2 and zirconia–carbon nanotube (CNT) composite. The effect of the processing route and the CNT's addition on the microstructure, fracture/mechanical and electrical properties of the zirconia has been investigated at room temperature. The microstructure of the sintered and hot-pressed monolithic ZrO2 consists of a submicron-sized grains. The matrix of the ZrO2–CNT composite consists of a grains with even smaller size (approximately 140 nm) with relatively well dispersed carbon nanotubes. The hardness and the indentation toughness of the sintered monolithic zirconia are 1297 kg/mm2 and 8.01 MPa m0.5 and of the hot-pressed monolithic zirconia 1397 kg/mm2 and 6.24 MPa m0.5, respectively. The addition of the CNT's decreased the hardness and indentation toughness to 830 kg/mm2 and 5.6 MPa m0.5 however the electrical resistivity decreased significantly in comparison to the monolithic zirconia to the value of 0.1 Ω cm.