木质复合磁性板材的制备及其电磁波吸收性能

主要研究以磁性纤维板作为芯材制备多层复合磁性板材,并对板材的电磁波吸收性能进行研究,为木质复合磁性板材的生产及其在电磁波吸收领域的应用提供理论和试验基础。通过化学原位共沉淀法制备得到磁性纤维,并将其压制成纤维板芯材,再通过热压法与普通单板制备多层板; 对所得样品分别进行(XRD)、傅里叶变换红外光谱分析(FT-IR)、振动样品磁强计(VSM)分析和网络矢量分析仪分析。结果表明,不同铁盐浸渍时间对磁性纤维的磁性产生较大差异,其中72 h样品的磁性最强,饱和磁化强度(Ms)达到20.52 emu/g,24 h样品磁性最弱,只有8.04 emu/g。同时,电磁波最大吸收强度对应的电磁波频率以及有效电磁波吸收频率范围均随磁性纤维板芯材厚度的增加而减小。另外,研究还发现,通过调节铁盐浸渍时间,木质复合磁性板材对电磁波吸收的最大值和针对的电磁波频率有效吸收范围均发生了变化,并且电磁波吸收性能随着铁盐浸渍时间的增加而增强,从而达到调节电磁波吸收性能的效果。最后,研究了多层木质复合磁性板材中磁性纤维板芯材的层数对其电磁波吸收性能的影响,结果显示,在其他条件不变的情况下,随着磁性纤维板芯材层数的增加,其电磁波吸收强度由-14.14 dB(3层)增加到-60.16 dB(7层)。
In this paper, the multi-layer magnetic wood product was fabricated by hot-pressing the magnetic fiber board and the normal wood veneers layer by layer. The obtained magnetic fibers by in-situ chemical co-precipitation were used to fabricate magnetic fiber board by hot-pressing. The X-ray diffraction(XRD), Fourier Transform infrared spectroscopy(FT-IR), Vibrating Sample Magnetometer(VSM)and the network vector analyzer were used to investigate the composition, magnetic and electromagnetic wave absorption properties of the prepared samples. The concentration ratio of Fe3+ and Fe2+ in the impregnating solution was 2:1, the concentration of ammonia was 25%. The magnetic properties of magnetic fibers were different due to the different ferric salt impregnation time. The magnetism of 72 h samples was largest with the saturation magnetization of 20.52 emu/g while the one of 24 h samples was only 8.04 emu/g. The magnetic wave absorbing capacities of the magnetic fiber boards obtained with 72 h impregnation time exhibited strongest adsorption capacities of -51.01 dB with a thickness of 3.00 mm. It was proved that this outstanding EMW absorption property was due to the strongest dielectric loss, the optimal magnetic loss, and the dipole relaxation polarization. Meanwhile, the obtained matching frequency of the fabricated multi-layer magnetic board towards the largest electromagnetic wave shielding property shifted to the low-frequency region with the increasing thickness of the contained magnetic fiber board. In addition, the magnetic wave shielding capacities of the multi-layer magnetic boards could be adjusted via the iron salt impregnation time. Finally, the influence of the number of the magnetic fiber boards in the multi-layer magnetic wood on the shielding performance was investigated. The results showed that when the other conditions remained unchanged, the electromagnetic shielding capacities of the obtained multi-layer boards increased from -14.14 dB(3-layer board containing 1-layer magnetic fiber board)to -60.16