短切SiCf/LAS复合材料的显微结构与介电性能

Microstructure and Dielectric Properties of Chopping SiCf/LAS Composites

摘要:

采用热压烧结法制备出致密的短切SiCf增强LAS玻璃陶瓷复合材料，并讨论保温时间与热压压力对复合材料介电性能的影响。结果表明，测试频率在8~12 GHz之间，复合材料复介电常数实部ε′由基体的7.6上升到10~100，虚部ε″由基体的0.34上升到40~160，介电损耗tgδ由基体的0.04上升到1~20，并具有明显的频散效应。随保温时间的延长或热压压力的提高，复合材料ε′增大，ε″与tgδ减小。此外，断口形貌的SEM观察表明，随保温时间的延长或热压压力的提高，复合材料界面层变厚。

Abstract:

The chopping SiCf/LAS composites were prepared by the hot-pressing method. The effects of hot-pressing time and pressures on the microstructures and the dielectric properties of the composites were researched. Compared with the LAS matrix and the SiC fibre, the results of dielectric constant testing in the range of 8-12 GHz indicate that the dielectric constant real part, imaginary part and dielectric dissipation of all samples increase by 1-3 orders of magnitude, and show obvious frequency dispersion effect. Their real parts increase while their imaginary parts and dielectric dissipations decline with the increase of the hot-pressing time or pressures. The SEM fractographs show that the composite interfacial films between the fibre and the matrix are thickened with the increase of the hot-pressing time or pressures.