Abstract
Microfracture in piezoceramics influences on its piezoelectric properties and their relationship can lead to development of self-diagnosing material using the piezoelectric properties. In this study, Vickers indentations were carried out to introduce small cracks in PZT specimens the specimens were subjected to a hitting test for evaluation of the piezoelectric properties. Then PZT specimens were bent to extend cracks on the surface of the specimen and the piezoelectric properties were measured. The waveform of a piezoelectric signal had a first positive peak and a second negative peak. An amplitude ratio (rp) of the first peak to the second peak was used to evaluate the piezoelectric properties of specimens. The ratio rp increased with the number of the Vickers indentation on the surface of specimens. When an interval of indentation positions is 0.3 mm, cracks coalesced. When the indentation array is perpendicular to hitting and poling directions, rp increased with the number of Vickers indentation. Following repeated bending of the specimen, the crack propagated successively to increase the ratio rp. Under the same loading conditions rp-crack propagation curves showed the same change and the same increasing ratio of rp occurred just before breaking of specimens. These results show the possibility of prediction of fracture in PZT by measurement of the piezoelectric properties.
