科研之友
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摘要
Graphite fibers with large diameter(~50 μm)have been prepared from mesophase pitch by melting-spinning,oxida-tive stabilization,carbonization and further graphitization.Then the one-dimensional carbon/carbon composites were fabricated by hot-pressing the graphite fibers with phenolic resin,carbonization and graphitization as well as subsequent chemical vapor infiltration and graphitization treatment(HP CVI).The products prepared by above process were densified again by second CVI and graphiti-zation treatment(HP 2CVI)to explore the influence of pyrolytic carbon(PyC)on the thermal properties of the C/C composites.The crystal structure,optical texture and morphologies of the C/C composite were investigated by X-ray diffraction(XRD),field emission scanning electron microscopy(SEM)and polarized light microscopy(PLM)analyses.The thermal diffusivities of the C/C composite along the axial and radial direction of the graphite fiber at room temperature were also tested.The results show that the density of the C/C composite after twice CVI treatment is about 1.63 g/cm3.The thermal conductivities of the C/C composites a-long the axial and radial direction of graphite fiber are 615.51 W/mK and 20.56 W/mK,respectively.The anisotropic ratio of the thermal conductivities along different direction is about 30 :1.The PyC oriented along the graphite fiber possess obvious anisotropic structure and the introduction of the PyC effectively improves the mechanical and thermal properties of the C/C composite.
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单位武汉科技大学; 湖北省煤转化与新型炭材料重点实验室
