Although the electromagnetic-coupling chemical vapor infiltration(E-CVI)has been proven of a high-efficiency technique for producing carbon fiber reinforced pyrocarbon(PyC)matrix(C/C)composites,a deep understanding of the deposition kinetics and mechanism of PyC matrix is still lack.In this work,a deposition model with uniform electric field but gradient magnetic field was set up by using unidi-rectional carbon fiber bundles as the substrates to investigate the deposition kinetics and mechanism.Meanwhile,the polarizability,and the chemical adsorption and dehydrogenation barriers of hydrocarbon were simulated based on the density functional theory(DFT)and the Climb-image nudged elastic band method,respectively.The E-CVI process exhibited extremely high PyC deposition rates of 8.7,11.5,16.5 and 22.7 nm/s at 700,750,800 and 850℃,respectively,together with a significantly low apparent ac-tivation energy of 57.9 kJ/mol within the first 5 min.The PyC deposited at different temperatures with different time shows a smooth laminar structure with low coherent length and graphitization degree.The theoretical calculation and simulation results indicated that the electrons existing on the carbon fibers and the accelerated motion of radicals with preferred orientation forced by the derived magnetic field have reduced the energy barrier for the deposition process,thereby resulting in low apparent activation energy and high PyC deposition rate.The results of this work may shed a light on how to better direct the preparation of C/C composites by E-CVI process with high quality and efficiency.

Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Hefei 230026,China;Department of Physics,Southern University of Science and Technology,Shenzhen 518055,China;The 31st Research Institute of China Aerospace Science and Industry Corp,Beijing 100074,China

[1]Chenglong Hu;Rida Zhao;Sajjad Ali;Yuanhong Wang;Shengyang Pang;Jian Li;Sufang Tang-.Deposition kinetics and mechanism of pyrocarbon for electromagnetic-coupling chemical vapor infiltration process)[J].材料科学技术（英文版）,2022(06):118-127

pyrocarbon,unidi,Climb

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