Hydrogen-induced cracking and its anisotropy of a PZT ferroelectric ceramics

Abstract

Threshold stress intensity factor of hydrogen-induced cracking (HIC), K IH , of a lead zirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constant load using notched tensile specimens with poling direction parallel or perpendicular to the crack plane. The results show that K IH reveals anisotropy, and the threshold stress intensity factor for the specimen with poling direction parallel to the crack plane, K IH a , is greater than that perpendicular to the crack plane, K IH b similar to the anisotropy of fracture toughness, K IC . The normalized threshold stress intensity factor of HIC, however, does not reveal anisotropy, and decreass linearly with logarithm of hydrogen concentration, C 0 , i.e. K IH a / K IC a = K IH b / K IC b =0.4—0.15 ln C 0 . Therefore, the anisotropy of HIC is the same as that of the fracture toughness, and is due to the anisotropy of the stress-induced 90° domain switching.