微纳米SiC/环氧树脂复合材料的界面和非线性电导特性

以微米和纳米SiC为填料，制备了不同填料配比的微纳米SiC/环氧树脂(EP)复合材料。测试了微纳米SiC/EP复合材料的玻璃化转变温度、室温介电谱和直流电导特性。分析了填料与基体之间的界面对玻璃化转变温度、介电谱及直流电导特性的影响。实验结果表明，在微米和纳米SiC填料的共同掺杂下，随着纳米SiC填料含量的增加，微纳米SiC/EP复合材料的玻璃化转变温度先降低后升高。在相同频率下，微纳米SiC/EP复合材料具有更低的相对介电常数和低频损耗峰幅值。与EP相比，微纳米SiC/EP复合材料具备显著的非线性电导特性。与微米SiC/EP复合材料相比，微纳米SiC/EP复合材料具有更高的非线性指数和阈值电场强度。微纳米SiC/EP复合材料的非线性电导特性与SiC颗粒和EP基体之间的界面区密切相关。 

Interface and nonlinear conduction characteristics of micro-nano SiC/epoxy composites

Micro-nano SiC/epoxy (EP) composites with different filler proportions were prepared with micro and nano SiC as the fillers. The glass transition temperature, room-temperature dielectric spectrum and direct current (DC) conduction of the micro-nano SiC/EP composites were measured. The effects of the interface between filler and matrix on the glass transition temperature, dielectric spectrum and DC conduction characteristics were analyzed. The results show that when the micro and nano SiC fillers are used together, the glass transition temperature of micro-nano SiC/EP composites decreases first and then increases with the increasing nano SiC filler content. At the same frequency, the micro-nano SiC/EP composites have lower relative permittivity and low-frequency loss peak. Compared with EP, the micro-nano SiC/EP composites present significant nonlinear conduction characteristics. In contrast with micro SiC/EP composite, the micro-nano SiC/EP composites have higher nonlinear exponent and switching electric field. The nonlinear conduction characteristics of micro-nano SiC/EP composites are closely related to the interfacial region between SiC particles and EP matrix.