用于电磁波吸收的碳纳米管水泥基复合材料

Cement-based composites filled with carbon nanotubes for electromagnetic wave absorption

采用弓形法对多壁碳纳米管(MWCNTs)水泥基复合材料的吸波性能进行了实验研究。结果表明,当MWCNTs掺量为0.6%(质量分数)时,厚度为25mm的试样在2.9GHz处获得最强吸收峰值-28dB,并能够在2～8GHz范围内对出现在吸收峰值附近的电磁波进行充分吸收;厚度为35mm的试样在8～18GHz表现出良好的宽频吸波性能。当MWCNTs掺量为0.9%(质量分数)时,水泥基复合材料在8～18GHz低于-10dB的带宽达到7.1GHz。力学强度测试结果表明MWCNTs在一定掺量范围内改善了水泥基材料的力学强度,但掺量的继续增大会导致力学强度的下降。MWCNTs掺量为0.9%(质量分数)的水泥砂浆抗压强度为60.2MPa,抗折强度为10.2MPa,虽然较空白试样有所下降,但仍有较高的力学强度。

In-situ Al3 Ti/Al composites were synthesized by direct melt reaction method under low frequency elec- tromagnetic field in A1-K2 TiF6 system. The effects of low-frequency electromagnetic field on the reinforced par ticles in A13Ti/A1 composites with different parameters such as input current intensity and electromagnetic frequency were investigated by SEM. The mechanism in-situ synthesized A13 Ti/A1 composites under low frequency electromagnetic field was investigated. The result shows that when the induction coil input current was 200A, electromagnetic frequency was less than 5Hz, magnetic field action time was 3-5min, Al3Ti/A1 composite with small size and uniform distribution has been gained. Within a certain range, increasing the current or increasing the frequency, the time of the magnetic field is reduced accordingly. But the parameters can not be increased indefinitely, otherwise the particles will be removed.