EFFECT OF HIGH-PRESSURE TREATMENT ON THE MECHANICAL-PROPERTIES OF Y-TZP

TZP (tetragonal zirconia polycrystal), has a higher toughness than pure ZrO//2. In the present work, Y//2O//3-doped TZP (Y-TZP) was treated at high pressure and the mechanical properties (hardness and toughness) were examined. The volume fraction of the monoclinic phase (V//m) was about 20%; however, the V//m of the high pressure treated specimens (except the specimens treated at room temperature) was low, e. g. 7% for the specimen treated at 5 GPa, 1400 degree C. Therefore, the effect of the stress-induced transformation did not contribute to the toughening. X-ray diffraction analysis showed that residual stress accumulated in the tetragonal lattice after the high pressure treatment. The residual (compressive) stress could be considered an agent of the toughness improvement.