串联2—2复合材料的介电击穿研究

研究了串联2－2型复合材料的介电击穿特性。串联2－2型压电复合材料结构较为简单，它是研究具有复杂连通性压电复合材料的基础。根据能量守恒定律，推导出串联2－2复合材料中压电陶瓷PZT层上和聚合物PVDF层上的电场强度Ec、Ep。由于压电陶瓷的介电常数εc(≈1600ε0)远远大于聚合物的介电常数εp(≈12εo)，因此Ep远远大于Ec。尽管PVDF的介电强度高于PZT的介电强度，但由于Ep远远大于Ec，所以串联2－2型压电复合材料的介电击穿往往是从聚合物层开始的，最后导致复合材料整体被击穿。对理论计算进行了实验验证，结果表明：在PZT含量较低时，计算值与试验值比较接近，但随着复合材料中PZT含量的提高，二者的偏差越来越大。文章最后定性讨论了在高PZT含量时复合材料的计算值与试验值偏差较大的原因。

Study on Dielectric Breakdown of 2-2 Piezoelectric Composites in Series

Properties of dielectric breakdown of 2-2 piezoelectric composites in series were studied．Structure of 2-2 piezoelectric composites in series was simple，so the study on piezoelectric composites with complicated connectivity could be based on 2-2 composites．According to energy conversation law，electric field strength Ec and Ep of piezoelectric ceramic PZT layer and polymer PVDF layer in the composites were derived，respectively．Due to dielectric constant of piezoelectric ceramic，εc≈（1 600 ε0）εp（≈12 ε0），dielectric constant of polymer，Ep was far more than Ec．Dielectric strength of PVDF was stronger than that of PZT，but Ep was far more than Ec，so that dielectric breakdown of 2-2 composites first occurred in polymer layers，and then composites was destroyed by a complete breakdown．The theoretic calcuations were verified through experiments．The results showed that experimental values are in good agreement with calculated values at low PZT volume content．With increasing of PZT content，the bias between them became greater and greater．Finally，the reasons for the bias becoming greater were qualitatively discussed．