Influence on crack nucleation and propagation on the piezoelectric properties of PZT

Microfracture in piezoceramics influences on its piezoelectric properties a nd their relationship can lead to development of self-diagnosing material u sing 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 specim en and the piezoelectric properties were measured. The waveform of a piezoe lectric signal had a first positive peak and a second negative peak. An amp litude ratio (r(p)) of the first peak to the second peak was used to evalua te the piezoelectric properties of specimens. The ratio r(p) 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 in dentation array is perpendicular to hitting and poling directions, r(p) inc reased with the number of Vickers indentation. Following repeated bending o f the specimen, the crack propagated successively to increase the ratio r(p ). Under the same loading conditions r(p)-crack propagation curves showed t he same change and the same increasing ratio of r(p) occurred just before b reaking of specimens. These results show the possibility of prediction of f racture in PZT by measurement of the piezoelectric properties.