Amplitude-dependent damping of PSZ with sinter defects

Samples of 3Y-PSZ (with yttria partially stabilized zirconia) ceramics were produced in a form of rectangular bar by uniaxial pressing with subsequent sintering and grinding. In some samples crack-type defects were induced under the larger surfaces by green-body pressing with very high pressure. The strain amplitude-dependent damping of these samples was measured in a single cantilever arrangement as the logarithmic decrement of free decaying bending vibrations. An increase of damping with strain amplitude was found. Compared to the samples without induced defects the samples with induced defects showed higher damping for all strain amplitudes and their damping increases strongly with increasing strain amplitude. Moreover, in the samples with induced defects, the damping for bending vibrations perpendicular to the defect-affected surfaces is much lower than parallel to those. Damping of the samples could be increased by bending fatigue performed in the apparatus by which the damping was measured. After a heat treatment up to 300 °C a decrease of damping was found which could possibly indicate healing of cracks. The results demonstrate that the measurement of internal friction is a powerful tool for detection of typical flaws such as pressing or sintering defects or cracks and can be used for non-destructive testing of ceramics.