Hejun Li
Northwestern Polytechnical University
Composite numberChemical vapor infiltrationCeramicComposite materialFlexural strengthMaterials scienceCorrosionScanning electron microscopeAblationLayer (electronics)Cementation (metallurgy)CoatingChemical engineeringCarbonCarbon nanotubeChemical vapor depositionPyrolytic carbonReinforced carbon–carbonNanowireMicrostructure
660Publications
68H-index
13.2kCitations
Publications 655
Newest
#1Qiangang Fu (NPU: Northwestern Polytechnical University)H-Index: 56
#2Zhang Pei (NPU: Northwestern Polytechnical University)
Last. Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
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Abstract null null Carbon fiber reinforced carbon composites (C/Cs), are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields, owing to their superior performances. However, C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures. Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics (UHTCs) are valid to enhance the oxidation/ablation resistance of C/Cs, it's ...
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#1Xinfa Tian (NPU: Northwestern Polytechnical University)H-Index: 4
#2Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
Last. Tao Feng (NPU: Northwestern Polytechnical University)H-Index: 8
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Abstract null null SiC nanowires reinforced C/(PyC-SiC)n multilayered matrix composites (SM-CS for short) were prepared by combined with sol-gel and chemical vapor infiltration (CVI) method. Firstly, (PyC-SiOC)n multilayered structure was formed by cycles of impregnation and deposition. Then SiOC was transformed into SiC by heat-treatment, and (PyC-SiC)n multilayered structure would be obtained. At the same time, the PyC layer which was designed as the outmost layer could decrease gas supersatur...
1 CitationsSource
#1Qinchuan He (Shaanxi University of Science and Technology)H-Index: 1
#2Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
Last. Yiqun Wang (CDUT: Chengdu University of Technology)
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Abstract null null In chemical liquid vapor deposition (CLVD) technique, carbon preform density is a crucial factor to control the microstructure of C/C-ZrC-SiC composites, which also determines the ablation resistance. The effects of preform density on the microstructure and ablation behavior of CLVD-C/C-ZrC-SiC composites were studied. Results demonstrated the composites prepared from the preform with a density of 0.91 g/cm3 showed a dense microstructure and proper ceramic content. Under an ox...
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#1Xuemin Yin (NPU: Northwestern Polytechnical University)H-Index: 11
#2Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
Last. Jinhua Lu (NPU: Northwestern Polytechnical University)H-Index: 22
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Abstract To overcome the disadvantages of traditional powder electrodes, such as the insufficient performance, the aggregation of active materials, and the complex fabrication process, rationally constructing free-standing electrode materials with hierarchical architecture is an effective and promising method, which could further improve the electrochemical properties. Herein, using metal-organic framework nanoarrays (MOFNAs) as self-sacrificial templates and SiC nanowires (SiCNWs) network as na...
2 CitationsSource
#1Tiyuan WangH-Index: 5
#2Hejun LiH-Index: 68
Last. Shouyang ZhangH-Index: 19
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The microstructure of pyrolytic carbon significantly affects the performance of aircraft brake discs. In this study, to explore the effect of precursor on the microstructure of pyrocarbon, two types of pyrocarbon films were grown on the quartz glass substrates by isothermal isobaric chemical vapor infiltration using methane and acetaldehyde as precursors. The microstructures of both the films and their formation mechanisms were investigated and compared. The thicknesses of the pyrocarbon films f...
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#1Chunyu Cheng (NPU: Northwestern Polytechnical University)H-Index: 7
#2Wei Xie (NPU: Northwestern Polytechnical University)H-Index: 3
Last. Qiangang Fu (NPU: Northwestern Polytechnical University)H-Index: 56
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#1Xuemin Yin (NPU: Northwestern Polytechnical University)H-Index: 11
#2Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
Last. Jinhua Lu (NPU: Northwestern Polytechnical University)H-Index: 22
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Abstract Rational construction of transitional metal oxides electrode materials with suitable structure and composition is an effective strategy of improving their electrochemical performance. Herein, novel MCo2O4 hierarchical nanofibers (H-MCo2O4NFs, M=Ni, Co and Mn) were fabricated by a multi-step self-templating method using electrospun nanofibers as precursors. Benefiting from the unique structure, such as numerous of vertically interlinked nanosheets on the surface and 1D interwoven nanofib...
1 CitationsSource
#1Tao Feng (NPU: Northwestern Polytechnical University)H-Index: 8
#2Wanbo Hou (NPU: Northwestern Polytechnical University)H-Index: 1
Last. Shifeng Wen (NPU: Northwestern Polytechnical University)H-Index: 3
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Abstract null null SiC nanowires (SiCnws) modified SiCf/HfC-SiC composites were prepared by precursor infiltration and pyrolysis (PIP) and chemical vapor infiltration (CVI) methods. The microstructure, flexural strengths, impact and impact-ablation tests of the composites with and without SiCnws were investigated. The results showed that after introducing SiCnws, not only the retention rate of HfC ceramic produced by PIP was increased obviously, but also the fracture displacement of the modified...
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#1H.F. Wang (NPU: Northwestern Polytechnical University)H-Index: 10
#2Jing-An Kong (NPU: Northwestern Polytechnical University)H-Index: 1
Last. Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
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Abstract null null To repair the damaged SiC coated C/C composites, a double-layer coating including a SiO2-Nd2O3 external layer (∼60 μm) and a Si-SiC inner layer (∼240 μm) was prepared by a slurry-based laser cladding technique, and the laser-ablation tests under two heat fluxes (23.89/39.81 MW·m-2) were performed. The spectrophotometer, X-ray diffraction, scanning electron microscopy and 3D profilometer were used for characterization. For avoiding the secondary damage of laser-ablation, the la...
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#1Tiyuan Wang (NPU: Northwestern Polytechnical University)H-Index: 5
#2Qiang Song (NPU: Northwestern Polytechnical University)H-Index: 26
Last. Hejun Li (NPU: Northwestern Polytechnical University)H-Index: 68
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Abstract Carbon fiber (CF)/epoxy composites with hybrid nanofillers were prepared by electrophoretic deposition (EPD) of silicon carbide nanowires (SiCnws) on CFs, followed by in-situ grafting of graphene via chemical vapor deposition (CVD). The effects of SiC nanowires/graphene hybrid nanofillers on interlaminar shear strength (ILSS), flexural property, and through-thickness thermal conductivity of CF/epoxy composites were investigated. Due to the incorporation of SiCnws and graphene, the inter...
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