Preparation And Property Research Of Carbon-based Composite Fibers Fabricated By Electrospinning

Carbon fiber?CF?is a special fiber material composed of carbon elements.It has the characteristics of high temperature resistance,friction resistance,electrical conductivity,thermal conductivity and corrosion resistance.It is an important material in defense military and civil use.This thesis is based on the experimental basis of preparing carbon fiber by electrospinning,combined with hydrothermal synthesis,blending doping,polymer conversion and other technologies,three composite carbon fiber materials of TiO₂-C,SiCN and Fe-SiCN have been prepared successively.The performance and mechanism of composite fibers were systematically studied.The main contents are as follows:?1?A series of TiO₂nano-array@carbon composite flexible fiber felts are prepared using electrostatic spinning technology and hydrothermal synthesis.XRD,SEM,TEM and Zeta potentials are used to characterize the structure,morphology and surface charge properties of the samples.The growth mechanism of TiO₂nanoarrays with different morphologies is discussed,and the dye removal performance of a series of samples is evaluated by the degradation effect of methine blue?MB?.The experimental results show that the doping of a proper amount of titanium dioxide particles can significantly improve the flexibility of carbon fibers,and improve the hydrophilic properties of the carbon fiber surface,which is beneficial to the growth of titanium dioxide on carbon fibers;With the increase of hydrothermal time,titanium dioxide nanoarrays grow most densely along the?110?crystal plane,the negative charge on the carbon fiber surface is enhanced,and the removal effect of methine blue is better.?2?Through the combination of polymer derivatization method and electrostatic spinning technology,a series of SiCN composite carbon fibers were prepared at different calcination temperatures?1000?1400°C?.XRD,FT-IR,TEM,SEM,XPS and Raman spectroscopy were used to study the phase composition,chemical structure,morphology and carbon crystalline state of SiCN fibers.In addition,a vector network analyzer was used to study the electromagnetic properties of SiCN fibers.The results show that as the heat treatment temperature increases,the amorphous carbon content increases,which can significantly adjust the dielectric properties of SiCN fibers.The SiCN fiber calcined at 1300°C has the largest dielectric loss tangent and the best electromagnetic wave absorption performance.The maximum dielectric loss tangent is 0.49,and the effective absorption bandwidth for electromagnetic waves is 4.59 GHz?11.8?16.4 GHz,RL<-10 dB?,with an RLmin value of-31.1 dB at a thickness of 2 mm.?3?On the basis of experiment?2?,nano-iron oxide particles were added to the precursor solution as an iron source to prepare a series of iron-doped SiCN composite carbon fibers?Fe-SiCN?,the effects of nano-iron oxide doping on the microstructure,phase composition,electromagnetic parameters and electromagnetic wave absorption properties of SiCN fibers were studied.The results show that:under the calcination condition of 1100°C,the iron oxide in the fiber is reduced to elemental iron,and a Si₃N₄crystal layer is formed on the surface,which exists in the composite carbon fiber in the form of Si₃N₄@Fe core-shell structure.Further research found that with the increase in the amount of nano-iron oxide particles,the iron content in the composite fiber was increased,and the recrystallization was significantly enhanced;when the iron oxide doping amount reached 0.2wt%,the Fe-SiCN composite carbon fiber had the largest electromagnetic wave absorption performance.At a thickness of1.5 mm,the effective absorption bandwidth of the sample for electromagnetic waves is 4 GHz?13.4 GHz-17.04 GHz,RL<-10dB?,and its reflection loss reaches-22.68dB?at a frequency of 12.4 GHz?.