Co-doped samples of 7YSZ with Yb3+, Ce4+ and Nb5+ having high porosity are subject to Vickers hardness testing. Fracture toughness KIC values are obtained by measuring linear and non-linear crack geometries. Three separate means are used to calculate the fracture toughness and to investigate the associated trends. It is confirmed that high amounts of retained tetragonal zirconia improve fracture toughness, while elevated amounts of monoclinic zirconia lower overall fracture toughness. The experimental trend for increasing KIC is Nb:7YSZ<Yb:7YSZ<7YSZ<Ce:7YSZ; however, this trend is qualitative as the Young's modulus values for different samples are corrected for porosity using an equation that does not generally apply to indentation techniques.
LiP, ChenI, Penner-HahnJ: J. Am. Ceram. Soc., 1994, 77, 118–28.
3.
PetitjeanJ: ‘On the thermodynamic stability and microstructure of variably cooled and Co doped Y2O3–ZrO2 for application to thermal barrier coatings’, MSc thesis, Carleton University. Ottawa, Canada, 2009.
