在制备石墨烯/聚乳酸(PLA)复合材料的基础上,利用熔融沉积成型技术快速制备了单层均质样件,研究了石墨烯含量对其电磁参数的影响规律,并基于传输线理论计算分析了其吸波效果;选择石墨烯含量较低的复合材料作为透波层的打印材料,石墨烯含量较高的复合线材作为吸收层和再次吸收层的打印材料,并基于四分之一波长匹配理论确定了吸收层、再次吸收层的匹配厚度范围。设计制造了由不同石墨烯/PLA复合材料组合而成的三层吸波体,测试结果表明:三层吸波体的吸波效果远优于单层均质吸波体,且当选取石墨烯质量分数分别为5%、7%、8%的复合材料作为透波层、吸收层和再次吸收层打印材料时,可以获得最佳的吸收效果,此吸波体在13.3~18 GHz频段内的反射率均小于-10 dB,在17 GHz时有-30 dB的最大吸收峰值。

In this study, single-layer homogeneous samples are rapidly prototyped using fused deposition modeling (FDM) based on the preparation of graphene/polylactide (PLA) composite. Further, the effects of different graphene contents on the electromagnetic parameters are investigated. The wave absorption effect is calculated and analyzed according to the transmission line theory. A composite exhibiting low graphene content is selected as the printing material of transparent layer, whereas a composite exhibiting high graphene content is selected as the printing material of absorption and reabsorption layers. Furthermore, the matching thickness range of the absorption and reabsorption layers is determined using the quarter-wavelength matching model. Subsequently, a three-layer wave absorber comprising different graphene/PLA composite is designed and manufactured. The experimental results denote that a three-layer wave absorber performs significantly better than a single-layer homogeneous wave absorber. The optimal wave absorption effect can be observed when the composites with the graphene mass fractions of 5%, 7%, and 8%, are used as the printing materials of transparent, absorption, and reabsorption layers, respectively. Finally, the reflectivity of such wave absorber in the band of 13.3-18 GHz is less than -10 dB, and the maximum absorption peak is -30 dB at 17 GHz.