Xi’an Jiaotong University “CEJ”: Preparation of Carbon Fiber/Graphene Composites by Joule Heating for Lightning Protection and Electromagnetic Interference in Aerospace

 

Brief Introduction Of The Results

 

Lightweight and low-cost protective layers of composite materials are the future needs of the aviation industry. However, current methods cannot meet the dual requirements of lightning strike protection and electromagnetic interference at the same time. In this paper, the team of Associate Professor Wang Ben from Xi’an Jiaotong University published a paper titled “Joule heating synthesis of carbon fiber/graphene 3D crosslinked structure for lightning strike protection and electromagnetic interference in aerospace composites” in the journal Chemical Engineering Journal. The study prepared an internal continuous carbon fiber felt/graphene hybrid film through a roll-to-roll Joule heating process. The film has excellent electrical and thermal conductivity and stronger mechanical properties.

 

Graphene is introduced into the carbon fiber felt as a conductive bridging medium, and it is covalently bonded to the carbon fiber through Joule heating to construct a three-dimensional structural network. The hybrid film with 19 wt% graphene content has the best conductivity, and the electrical conductivity and thermal conductivity after epoxy resin curing are increased by 5.2 times and 1.8 times, respectively (2690 S-m-1 vs. 518 S-m-1, 0.49 W-m-1-K-1 vs. 0.27 W-m-1-K-1).

 

In addition, the hybrid film can also be used as a protective layer on the surface of the composite material. After being struck by lightning with a peak of 100 kA, the damage rate of the composite material was significantly reduced, and the residual strength remained at 98%. In addition, the electromagnetic shielding effect in the X-band was improved by 51.94 dB, which shows that the prepared hybrid film is a promising material to replace commercial copper mesh.

 

 

Figure 1. (a) Schematic diagram of the main preparation process. (b) Demonstration equipment and sample preparation. (c) Some samples after Joule heating.

 

Figure 2. (A-C) Internal structure and fiber morphology of pristine CFF. (d-f) Interaction between fibers and GO sheets in infiltrated CFF. (G-I) Morphological transformation of the internal structure after Joule heating.

 

 

Figure 3: (a1-a3) TEM images of pristine CF, CF-GO, and CF-graphene. (b) XRD patterns of pristine CFF and modified CFF. (c) Changes in the arrangement of GO sheets during Joule heating. (d) Formation mechanism of covalent bonds between CF and graphene. (e) SEM images of two independent CFs cross-linked with graphene sheets. (f) TEM image of the cross-linked region between CF and graphene. (g) TEM image of the cross-linked region between graphene sheets.

 

 

Figure 4. (a) Electrical conductivity as a function of graphene content. (b) Electrical conductivity as a function of temperature at the optimal graphene content. (c) Raman spectra at different heating temperatures. (d) Comparison of electrical conductivity at different heating temperatures. (e) Raman spectra at different heating times. (f) Comparison of electrical conductivity at different heating times. (g) Comparison of electrical and thermal conductivity of original CFF and modified CFF with optimal graphene content after hot press curing with epoxy resin. (h) Thermogravimetric curves of original and modified CFF.

 

Figure 5. (a) Stress-strain curves and damage behaviors of original and modified CFFs with different graphene contents. (b-c) SEM images of curled fibers in unstretched CFFs and straightened fibers in the fractured part after stretching. (d-e) Micromorphology of modified CFFs on the crack cross section. (f1-f2) Optical microscopy images of the cross-linked region before and after in situ stretching. (g) Schematic diagram of the fracture mechanism.

 

 

Figure 6. Digital images of CFRP, CFRP-Cu, CFRP-CFF, and CFRP-modified CFF (a1-a4) before and after impact. CT images of (c) pure CFRP, (d) CFRP-Cu, (e) CFRP-CFF, and (d) carbon fiber reinforced modified CFF.

 

 

Figure 7. (a) EMI SET of the sample. (b) Average EMI SE of the sample. (c) Mechanism of EMI shielding enhancement.

 

3 Summary

 

This study used low-cost carbon fiber felt and graphene sheets, and achieved rapid reduction of graphene sheets through efficient Joule heating. The extremely high temperature (2800 ℃) promoted the covalent cross-linking between carbon fiber and graphene sheets, constructed an internal continuous three-dimensional conductive network, and the conductive and mechanical properties of the modified carbon fiber felt were also improved. The significant improvement in conductive properties reveals the application potential of this material in the field of lightning protection.

 

In summary, the more available raw materials and convenient processing technology proposed in this study provide a possible alternative to commercial copper mesh, and provide a basis for the widespread application of carbon materials in aviation, communications, electronics and heat dissipation systems.