抄録
In this study, two types of PZT (lead zirconate titanate, Pb(Zr,Ti)O3) ceramics were used. One is low-Qm PZT, mainly used as signal devices. The other is high-Qm PZT, which is utilized high power conditions applied in piezoelectric transformers, actuators and ultrasonic motors. The Qm is a mechanical quality factor (Qm = s'/s”, s* = s'-js”, where s* is an elastic compliance). In order to obtain a high output power, PZT ceramics must be driven at a high vibration level. This causes heat generation. Recently, the demand of high-Qm PZT is increased. Because, the high-Qm PZT is utilized under the condition of continually stretch and shrink, to avoid premature failure, the high-strength piezoelectric ceramics is required. The mechanical properties including fatigue of Pb(Zr,Ti)O3(PZT) ceramics were investigated in this study.
The bending strength, Young's modulus and Vicker's hardness of high-Qm PZT were higher than those of low-Qm ones. It was found that by the fatigue test, as the applied stress of high-Qm PZT increased, the number of cycles to fracture decreased remarkably, compared with that of low-Qm ones. The SEM fractographs of fatigued high-Qm specimens indicated that inter-granular fracture occured preferentially. The difference of these mechanical properties and fatigue behavior between low-Qm and high-Qm depended on the inter-granular fatigue crack which proceeded along the grain boundary in high-Qm material.
