Synergistic action of mechanisms for increasing the impact toughness of ceramic composites based on ZrO2

Abstract

The structure and properties of ceramic composites based on zirconium dioxide with the addition of carbon nanotubes have been studied. It is shown that introduction of carbon nanotubes leads to insignificant increase of Young's modulus and hardness of ZrO2–CNT ceramics. It is shown that the increase of fracture toughness in ZrO2–CNT composites is provided by synergistic manifestation of mechanisms increasing crack propagation work. Several mechanisms of energy dissipation are realized in ZrO2–CNT ceramic composites, namely phase transition of tetragonal to monocline modification of ZrO2 and bridging of cracks by carbon nanotubes. It is worth noting that the contribution of martensitic transformation to crack resistance decreases as the volume fraction of carbon nanotubes in the zirconia matrix increases, which is caused by a decrease in the grain size of the tetragonal zirconium dioxide phase and thus with its transition to a stable state.