Preparation And Properties Of Fe₃O₄@RGO/EP/CF Wave Absorbing Metamaterials

The development direction of wave absorbing composites is"thin,light,wide and strong",therefore,the development of traditional structural wave absorbing composites is increasingly restricted,while metamaterials have more and more flexible designs,which are more in line with the development of wave absorbing composites.In this paper,Fe₃O₄@RGO,a magnetoelectric two-component wave-absorbing particle with stable performance,was prepared by green mass production process and used as filler with epoxy resin matrix to obtain Fe₃O₄@RGO/EP wave-absorbing composite.In addition,the Fe₃O₄@RGO/EP wave absorbing metamaterial was designed using a combination of simulation and experiment in CST Microwave Studio,and the preparation process of its reflective layer carbon fiber composite(CFRP)was investigated to finally prepare Fe₃O₄@RGO/EP/CF.the main research contents and results are as follows.(1)The temperature for the preparation of Fe₃O₄@RGO by co-precipitation method was determined to be 90°C by VSM,Raman and VNA,and the optimal addition of green reducing agent ascorbic acid was 1.5 times the mass of GO.The microscopic morphology of Fe₃O₄@RGO was determined by SEM,TEM and HRTEM,and the in situ growth of Fe₃O₄synthesized by the co-precipitation method on the surface of graphene sheets was demonstrated,and the average particle size of Fe₃O₄ overlaid on RGO was determined to be16.36 nm.The characterization by XRD,Raman and FT-IR proved that the Fe₃O₄@RGO composite functional particles was successfully synthesized.Its effective absorption band after mixing with paraffin wax at 50%fill rate is 9.19-11.31 GHz(bandwidth of 2.12 GHz),and the minimum reflection loss value of-12.88 d B is obtained at 10.22 GHz.The unit price of Fe₃O₄@RGO mass production is 11.67 RMB/gram.(2)The above particles were prepared as Fe₃O₄@RGO/EP wave-absorbing composites,and a layered curing process was innovatively proposed to solve the problem of settling of the filler in the EP matrix due to its high specific gravity.The electromagnetic parameters and microwave absorption properties of Fe₃O₄@RGO/EP with different resin systems were analyzed,and composites with a filler mass of 33%and an effective absorption bandwidth of4.10 GHz(11.33 GHz-15.43 GHz)below-10 d B were obtained,and the strongest absorption of-17.60 d B was achieved at 12.76 GHz.The above composite was sculpted as a metamaterial,and four modulation steps were proposed to simulate the design cell structure to finally obtain Fe₃O₄@RGO/EP absorbing metamaterials with an effective absorption bandwidth of 11.44 GHz(4.73 GHz-8.96 GHz and 10.79 GHz-18 GHz)below-10 d B as measured by the bow method,where the strongest absorption was reached at 18 GHz of-22.77 dB.(3)The process preparation of the reflective layer CFRP of metamaterials was investigated,the curing process of HHPA/EP resin system under different molding methods was determined,the factors affecting the mechanical properties of carbon fiber composites during preparation were discussed,and the CF lay-up method was determined to be[0°,90°]orthogonal lay-up.The best overall mechanical properties of the CFRP prepared by hot press molding were achieved with bending modulus of 72.3 GPa,bending strength of 770 MPa,and impact toughness of 203 k J/m~2.The microwave absorption performance of Fe₃O₄@RGO/EP/CF absorbing metamaterials was measured by bowing method,and the effective absorption bandwidth below-10 d B was 11.20 GHz(effective bandwidth The effective absorption bandwidth is 11.20 GHz below-10 d B(the effective bandwidths are distributed between 4.71 GHz-8.62 GHz and 10.71 GHz-18 GHz),where the strongest absorption is reached at-25.71 dB at 18 GHz.