Fe_xN-膨胀石墨复合材料的制备及其电磁屏蔽效能

Preparation of Fe_xN/expanded graphite for electromagnetic shielding

以醋酸铁为前驱体、乙醇为溶剂,通过浸渍、干燥、H2预还原以及NH3氮化,将粒径为100~600nm磁性纳米FexN颗粒植入膨胀石墨(EG)得到FexN-EG复合材料,随氮化温度升高FexN物相主要为Fe4N、Fe2~3N、FeN,所得FexN饱和磁化强度较高,为软磁材料。改变氮化温度可以调控植入的纳米FexN中N原子的比例,从而可以改变FexN的磁性,显著提高复合材料的低频电磁屏蔽效能,使其在较宽的频段内有好的电磁屏蔽效能。结果表明,400℃氮化时磁性颗粒物相以Fe4N为主,此时复合材料的电磁屏蔽效能最好,面密度仅为0.09 g/cm2的试样在300 kHz^1.5 GHz范围的电磁屏蔽效能达68.5~100 dB。

Using iron acetate as precursor and diethyl ether as solvent, FexN-EG composites were prepared by embedding FexN nanoparticles in the layers of expanded graphite （EG） by impregnating, drying, prereducing in 1-12 and nitriding in NH3. With increasing the nitriding temperature, FexN mainly consists of Fe4N, Fe2～3N and FeN. The FexN nanoparticles exhibt a higher saturation magnetization and particle sizes of mainly 100-600 nm, and are well spread on the layers of EG N atom percentage of FexN can be regulated by changing nitriding temperature to change the magnetic property of FexN, and resultantly improving shielding effectiveness （SE） for electromagnetic radiations at low frequencies. Since EG is electronically conductive and displays high SE at high frequencies, the composites exhibit good SE at a wide range of frequenciy. The magnetic property of the composites could be monitored through regulating the nitriding temperature, and it was found that the nitrided composites exhibited good SE. Specifically, the composite nitfided at 400℃ shows excellent SE from 68.5 at 300 kHz to 100 dB at 1.5 GHz when the areal density of the sample is only 0.09g/cm^2.