摘要:
利用数字图像相关性分析方法发展了全场应变光学测量技术,并原位实时测量了准静态单轴压缩下铁电PZT95/5陶瓷试件的轴向应变和横向应变.基于轴向应变、横向应变随着轴向应力的变化关系,讨论了极化状态和极化方向对PZT95/5铁电陶瓷的畴变与相变行为的影响.实验结果显示:单轴压缩下,未极化和Z轴极化PZT95/5铁电陶瓷都会发生畴变,而y轴极化PZT95/5铁电陶瓷则不发生畴变;畴变促使Z轴极化PZT95/5铁电陶瓷的轴向应变和横向应变同时快速地增长,而对未极化PZT95/5铁电陶瓷的应变增长的影响非常微弱,这种差异性归因于电畴极轴不同的取向分布特征;通过应变分解分析,验证了畴变与相变过程是解耦的,并界定了畴变应变和相变应变的影响范围;与Z轴极化PZT95/5铁电陶瓷相比,未极化PZT95/5铁电陶瓷的相变开始临界应力和相变结束应力减小,而Y轴极化PZT95/5铁电陶瓷则明显增大,由此推论畴变对相变有一定促进作用.基于放电特性的实测结果,还讨论了极化方向对极化PZT95/5铁电陶瓷去极化机理的影响.实验结果显示:Z轴极化PZT95/5铁电陶瓷去极化机理是畴变和相变的共同作用,其中畴变占主导地位,而Y轴极化PZT95/5铁电陶瓷的去极化机理仅是相变.
Abstract:
The digital image correlation technique is used for full field measurements of axial strain and transverse strain of PZT95/5 ferroelectric ceramics under uniaxial compression.Based on the variations of the axial strain and transverse strain with axial stress,the effects of poling state and poling direction of PZT95/5 ferroelectric ceramics on the domain switching and phase transformation behaviors are explored.Domain switching occurs in unpoled and Z-axis poled PZT95/5 ferroelectric ceramics separately,while domain switching in the Y-axis poled PZT95/5 ferroelectric ceramic is not observed.Domain switching strain in the Z-axis poled PZT95/5 ferroelectric ceramic has obvious influences on the developments of axial strain and transverse strain,but the influence of domain switching strain in the unpoled PZT95/5 ferroelectric ceramic is very weak,which can be attributed to the different random distribution characteristics of domain orientation.By the strain decomposition analysis,it is proved that the domain switching and the phase transition process can be decoupled,and domain switching strain and phase transformation strain can be distinguished successfully.Compared with the Z-axis poled PZT95/5 ferroelectric ceramic,the unpoled PZT95/5 ferroelectric ceramic has a small critical stress of phase transformation,while the critical stress of the Y-axis poled PZT95/5 ferroelectric ceramics is big,which may be concluded that the domain switching behavior favors the phase transformation process.The polarization released behavior of PZT95/5 ferroelectric ceramic also depends on the poling direction.The depolarization mechanism of Z-axis poled PZT95/5 ferroelectric ceramic is caused by both domain switching and phase transformation,and the Y-axis poled PZT95/5 ferroelectric ceramic is caused by only phase transformation.
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