Transient failure mode of (Ba,Ca)(Ti,Zr)O ₃ pulsed power capacitor based on electromechanical coupling mechanism

A (Ba,Ca)(Ti,Zr)O ₃ pulsed power capacitor (BCZTPPC) is used as the power source to provide an instantaneous energy shock in spacecraft systems. In this paper, a transient failure mode about BCZTPPC is discussed and illustrated by an electromechanical coupling mechanism after analyzing the consequences of ring down tests, images of destructive physical analysis, finite-element analysis and numerical analysis. Results obtained point out that if the discharge frequency of BCZTPPC is equal to natural frequency of dielectric material, a mechanical resonance would occur based on reverse piezoelectric effect. Such an electromechanical coupling progress can fracture the inner ceramic layers and form internal cracks across the inner electrodes. As a consequence, the high-voltage immediately destroys the capacitor by dumping all the energy on the these fractured areas the next time a discharge occurs since the cracks across inner electrodes can be seems as short circuit under a high applied voltage. It is concluded that such an instantaneous slightly overloaded mechanical energy shock caused by electromechanical coupling progress is fatal to a BCZTPPC.