An experimental study on the interface polarization of double-layered composite structure containing nonlinear dielectrics

This study deals with the polarization and depolarization currents of linear/nonlinear double-layered composites, and sets out to explore interface polarization and depolarization characteristics. The linear layer is pure low density polyethylene (LDPE) matrix. The nonlinear barrier layer is prepared by adding nanofillers (ZnO and SiC) to LDPE with different concentrations. Experimental results show that the species and amount of the nanofillers (ZnO and SiC) in nonlinear dielectrics and experimental temperature have a great influence on the polarization and depolarization of the double-layered composite structure containing nonlinear dielectrics. With the increasing of the concentration of nanofillers (ZnO) in nonlinear layer, polarization and depolarization currents all are increasing, and the relaxation times of polarization and depolarization are correspondingly prolonged. When nonlinear layer with concentration of ZnO are 9.09wt% and 16.67wt%, the polarization and depolarization currents are less than that of the same concentration of SiC. Under same experimental condition, the polarization and depolarization currents also increase with the amplitude of excitation voltage, and the relaxation time of polarization is much longer than the relaxation time of depolarization. The transient current at the moment of excitation voltage inversion is much larger than the polarization current.