| Lead Zirconate Titanate as one kind of piezo-ceramic, because of its good piezoelectrical properties and low material cost, is widely used in various electro-mechanical equipments.Piezo-ceramic will undergo an electrical degradation process after applying an electrical field, and the degradation process represents as the decrease of the resistance and the decay of the piezoelectrical properties. This electrical degradation phenomenon severely limits the lifetime and the performance of piezoelectrical products. However, the electrical degradation mechanism has not been completed and the testing methods of the life-time and the reliability of the piezoelectrical samples are currently based on the investigation of the leakage current through the samples, currently.This project had researched the influence of temperature, humidity on the electrical degradation progress, influence of electrical degradation progress on the black spot growth and the characterization of black spots. Through the research, new black spots observation method had been discovered, the relationships between temperatures, humidity, electrical degradation progress and slack spot growth has been investigated. It has been found that the rise of temperature/humidity will speed up the lead zirconate titanate piezoelectric ceramic electrical degradation process in the work circuit. The number and area of black spots were increasing during the degradation process, but average area of black spot changed little. The cross section morphology of black spots was first time observed directly by optical microscope. And through calculation, it was found that the black spotand electric breakdown was not one to one correspondence relation. A novel multi-breakdown theory had been proposed for explaining black spots growth. Those mechanism analysis is helpful to improve the existed electrical degradation theories. |
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