Toughening effect of multiwall carbon nanotubes on 3Y-TZP zirconia ceramics at cryogenic temperatures

Multiwalled carbon nanotubes (MWCNTs) could effectively improve the fracture toughness of 3 mol% Y2O3 stabilized zirconia (3Y-TZP) because of their excellent mechanical properties. Fully dense 3Y-TZP toughened by MWCNTs was fabricated by spark plasma sintering (SPS), and their mechanical properties at cryogenic temperatures were investigated. The hardness of 1.5 wt% MWCNTs toughened 3Y-TZP increased from 12.49±0.19 GPa to 15.10±0.45 GPa as the decrease of temperature from 293 K to 77 K, while the fracture toughness increased from 5.36±0.12 MPa m1/2 to 6.69±0.21 MPa m1/2. The enhancement mechanical properties at cryogenic temperature over room temperature were due to the unique high mechanical properties of ZrO2 matrix, elastic modulus, fracture surface energy and residual stress at cryogenic temperature. The above results suggested that the prepared MWNT toughened 3Y-TZP could be a candidate material for cryogenic application.