Determination of fracture toughness of zirconia ceramics with different yttria concentrations by SEVNB method

Abstract In this paper, we aim at determining the actual fracture toughness of three difference yttria concentrations (3 mol%, 5 mol% and 8 mol%) zirconia ceramics by single-edge V-notched beam (SEVNB) method. The notch root radius (ρ≈0.25 μm) introduced by femtosecond laser is smaller than the grain size of 3YSZ. As obtained KIc values for the three zirconia samples are 4.4±0.12, 2.8 ±0.11 and 1.6±0.05 MPa m1/2 for 3YSZ, 5YSZ and 8YSZ, respectively. However, for a notch root radius of 9 µm cut by a razor blade, the KIc value of 3YSZ is 6.2±0.47 MPa m1/2. The volume fraction of m-ZrO2 on fractured surface determined by XRD is found to be nearly equal to that of SENB method. Specifically, the load-deflection curves of SEVNB method under the loading rate of 0.05 mm/min, 0.03 mm/min and 0.01 mm/min exhibit a stable crack propagation behavior.