恒电场下BaTiO_3陶瓷压痕裂纹的滞后扩展

DELAYED PROPAGATION OF INDENTATION CRACKS IN A BaTiO_3 CERAMIC UNDER SUSTAINED FIELD

在硅油中加恒电场,研究了BaTiO3铁电陶瓷上维氏压痕裂纹的瞬时扩展和滞后扩展的规律.结果表明,当电场E≥2 kV/mm时,压痕裂纹能发生瞬时扩展,瞬时扩展量随外电场升高而升高.当E≤1.5 kV/mm后,裂纹不能瞬时扩展,但在恒电场下保持一定时间后,就开始滞后扩展,大约60 h后将止裂.电场愈小,发生滞后扩展的孕育期ti愈长;当E≤0.8 kV/mm后,压痕裂纹不发生滞后扩展.随电场升高,裂纹扩展量及平均扩展速率均升高.

Instant and delayed growths of indentation cracks in a BaTiO3 ceramic under sustained electric field in silicon oil have been investigated. The results show that the instant propagation of indentation cracks can occur when the field E greater than or equal to2 kV/mm, and the propagating amount increases with increasing the field. If E less than or equal to1.5 kV/mm, no instant growth but a delayed propagation will occur after an incubation time t(i) under sustained field. The crack will arrest after propagation for about 60 h. The smaller the field E, the longer the incubation time. No delayed crack propagation occurs within 100 h when the field E less than or equal to0.8 kV/mm. Crack increment and average growth rate increase with increasing the field.