Cyclic fatigue of zirconia ceramics
Uniaxial tension-compression fatigue behavior was studied for 3 mol% yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), 12 mol% ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP), and 8 mol% magnesia-partially stabilized zirconia (Mg-PSZ). Hysteresis loops, cyclic stress-strain curves, and lifetime data have been obtained. Additional experiments on fatigue crack growth under reverse loading were conducted using controlled surface flaws. The results form these studies have been used to obtain a comprehensive description of the fatigue deformation, damage and fracture behavior. Two distinct fatigue deformation mechanisms, microcracking was dominant in Y-TZP, while transformation plasticity was most evident in Ce-TZP and also in Mg-PSZ. The proportion of the plastic strain contribution due to these two mechanisms was dependent on the frequency, stress amplitude, and temperature, with transformation plasticity favored at lower frequency, higher stress, and lower temperature. Hysteresis in the stress-plastic strain curve reflects to the operation of forward, delayed phase transformation, reverse transformation, microcrack closure, and crack face sliding. Strain irreversibility was found to be closely related to the microstructure and more reversible in Ce-TZP and Y-TZP. Fatigue crack propagation in Y-TZP was found to follow a unique growth lay strongly dependent on the maximum stress intensity factor and quandratically dependent on the amplitude of the range of stress intensity factor. It applied for both surface flaws and internal flaws. The presence of residual stresses altered the growth mechanics so that an inverse growth rate dependence on the applied stress, reminiscent of the so-called short-crack behavior', was manifested. Fatigue striations resulting from alternate overload fracture and fatigue fracture during stress cycle was observed.
- Research Organization:
- Michigan Univ., Ann Arbor, MI (United States)
- OSTI ID:
- 7114653
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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