金红石颗粒尺寸对硅橡胶微波介电性能的影响

Effects of Rutile Particle Size on Microwave Dielectric Properties of Silicone Rubber

在107硅橡胶中分别添加纳米级和微米级金红石颗粒,通过室温固化制备金红石/硅橡胶复合材料。用X射线衍射仪、透射电镜和扫描电镜对陶瓷填料的相组成及微观形貌进行了表征,分析了金红石颗粒体积分数和尺寸对硅橡胶微波介电性能的影响。研究结果表明:在相同体积分数下,纳米级金红石/硅橡胶复合材料与微米级金红石/硅橡胶复合材料相比,介电常数ε_r较大,品质因数与谐振频率的乘积(Q×f)较低,两种复合材料的谐振频率温度系数τ_f相差不大。金红石颗粒体积分数为19%时,纳米级金红石/硅橡胶复合材料的ε_r为3.32,Q×f为2 604 GHz,τ_f为49×10^(-6)/℃。并且将介电常数εr试验值与3种理论模型的ε_r理论值进行对比,发现试验值比理论值偏低。

Rutile / silicone rubber composites were prepared by filling 107 silicone rubber with micro-and nanorutile particles respectively and by room temperature curing method. The phase composition and microstructure of the ceramic fillers were characterized by X-ray diffraction( XRD),transmission electron microscope( TEM)and scanning electron microscope( SEM). The effects of rutile particles volume fraction and size on the microwave dielectric properties of silicone rubber were investigated. The results show that for the same volume fraction,the permittivity ε_r of nano rutile / silicone rubber composites is higher than micro rutile / silicone rubber composites,while the product of quality factor and resonance frequency Q × f of nano rutile / silicone rubber composites is lower than that of micro rutile / silicone rubber composites. The temperature coefficient of resonance frequency τ_f of the two kinds of composites are similar. For 19% volume fraction of nano rutile,ε_r is3. 32,Q × f is 2 604 GHz and τ_f is 49 × 10^(- 6)/ ℃. The experimental values of composites permittivity were compared with three kinds of theoretical models,and it was find that the experimental values of permittivity are lower than the theoretical value.