中文摘要：

通过磁场辅助硫化工艺,制备了微米铁粉填充和排列的硅橡胶导电复合材料,比较了铁粉形状对材料组织和电性能的影响.测量结果发现,经过磁场处理的粒状铁粉体系渗流阈值为5%,最小电阻为106Ω,而纤维状铁粉体系渗流阈值仅为0.2%,最小电阻低于1Ω;前者在1010Ω前后出现正压阻效应和负压阻效应,而后者只出现负压阻效应.研究显示,纤维铁粉有较大的长径比,其排列组织的轴向导电性、抵抗变形能力大大优于粒状铁粉,因此决定了它们的复合材料电学性能的差异.

英文摘要：

Using a procedure of magnetic field vulcanization,the composites filled with granular or fiber-like aligned iron powder were prepared,and the microstructures along with electrical properties of composites were characterized and discussed.The results show that the percolation threshold is about 0.2% with a lowest resistance of 1 Ω for fiber-like powder filled system（F-system） in contrast with 5% with a lowest resistance of 106 Ω for the granular powder filled system（G-system）.Moreover,F-system exhibits a positive piezoresistivity to negative piezoresistivity transition at the resistance of about 1010 Ω,while G-system has the negative piezoresistivity through the pressure range studied.The difference above can be attributed to the effect of powder shape.Fiber-like powders seem to dedicate effectively to the axial electrical conductivity,and the resistance to strain for the composites is more than that of granular powders.