T800级碳纤维及石墨纤维微观结构的表征与性能分析

发布时间：2018-01-15 10:43

本文关键词：T800级碳纤维及石墨纤维微观结构的表征与性能分析　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：高性能碳纤维具有轻质高强、超高模量及低热膨胀系数等优点,是航天航空领域的关键材料,在国防经济建设中有着广泛用途。本文采用扫描电镜(SEM)、拉曼光谱仪(Raman)、透射电镜(TEM)、X射线衍射仪(XRD)及原子力显微镜(AFM)分别对三种高强系列碳纤维、三种高模系列石墨纤维的形貌、晶体结构、皮芯结构和相对硬度等微观结构进行了综合研究。提出了一种用于拉曼光谱和透射电镜测试的碳纤维截面(剖面)样品的制备方法,并着重利用拉曼光谱对日本东丽T800S及两种国产T800级碳纤维的径向、轴向及赤道方向均质化程度进行了表征分析,同时,结合TEM对三者的皮芯结构进行了研究,以期为我国高性能碳纤维的生产提供一定理论参考。SEM结果表明:东丽T800S的表面光滑,两种国产T800级碳纤维表面存在沿轴向取向性较好的沟槽,三者截面呈近圆形,其中东丽T800S截面圆度最高。三种高模系列石墨纤维表面沟槽比高强系列碳纤维深,且截面圆度比高强系列低,表面光滑度和圆度从大到小的顺序均为P311FCCM46JCCM40J,说明P311F石墨纤维的表面结构最致密,推测其石墨化温度最高。Raman光谱和TEM结果均表明,三种T800级碳纤维都存在一定的皮芯结构,JHT55的芯部直径约为1.60~1.78μm,而T800S和P278F的芯部直径均为1.13~1.60μm。此外,三种高强系列碳纤维皮层在赤道方向的也有一定的不均匀性,但东丽T800S整体的均一化程度远远优于两种国产碳纤维。三种高模系列石墨纤维的石墨化程度较高,从CCM40J到P311F,晶格条纹排列规整度增大,说明P311F石墨纤维接近理想石墨结构,拉伸模量较高。高强系列碳纤维中东丽T800S的微晶尺寸最大,且内部孔隙率低,这是其保持高强度的同时保持较高模量的重要原因。三种高模系列石墨纤维中,P311F石墨纤维的晶面间距d002最小,且三者的孔隙率从CCM40J、CCM46J到P311F依次降低。高强系列、高模系列碳纤维的硬度关系分别为:T800SP278FJHT55,P311FCCM46JCCM40J,与拉伸模量大小关系一致,表明用AFM表征碳纤维的硬度可在一定程度上反映其拉伸模量大小。碳纤维的宏观力学性能是由其微观结构综合决定的,表面光洁、细旦化、提高均质化程度、保留一定的非晶结构,有利于提高碳纤维强度;增大微晶尺寸、提高石墨层沿纤维轴的取向度、降低孔隙率,有利于提高石墨纤维的模量。
[Abstract]:High performance carbon fiber has high strength, high modulus and low thermal expansion coefficient and other advantages, is a key material in aerospace field, are widely used in the construction of national defense economy. In this paper, by using scanning electron microscopy (SEM), Raman spectroscopy (Raman), transmission electron microscopy (TEM), X ray diffraction (XRD) and atomic force microscope (AFM) respectively on the three series of high-strength carbon fiber, morphology, three kinds of high modulus graphite fiber series, crystal structure, skin core structure and the relative hardness and microstructure have been studied. A method for carbon fiber Raman spectroscopy and transmission electron microscopy test section is presented (section) preparation method the sample, and focused on the use of Raman spectroscopy in radial Japan Dongli T800S and two kinds of domestic T800 carbon fiber, axial and equatorial direction homogenization degree are analyzed, at the same time, combined with the skin core structure of three TEM were studied, in order for me The high performance carbon fiber production and provide a theoretical reference.SEM the results showed that the surface of Dongli T800S smooth, two kinds of surface made of T800 carbon fiber has good axial orientation along the trench, the three section is nearly circular, with the Dongli T800S circle section is the highest. Three series of high modulus graphite fiber surface groove than high strength a series of carbon fiber, and the section roundness ratio high strength low, surface smoothness and roundness of order from large to small was P311FCCM46JCCM40J, indicating the surface structure of P311F graphite fiber is the most dense, that the highest graphitization temperature.Raman spectra and TEM results showed that three kinds of T800 carbon fiber has skin core the structure of the JHT55 core diameter is about 1.60~1.78 m, and T800S and P278F core diameter of 1.13~1.60 M. in the three series of high strength carbon fiber cortex in the equatorial direction also has a certain uniformity, but Dongli T800S homogenization overall is much better than that of two kinds of carbon fiber. Three kinds of high modulus graphite fiber series high graphitization degree, from CCM40J to P311F, lattice fringe ordered degree increases, indicating that P311F is close to the ideal structure of graphite graphite fiber, the tensile modulus is higher. The crystallite size of high strength carbon fiber series of Middle East Li T800S the maximum, and this is the low porosity, high strength and high modulus. The main reason of the three series of high modulus graphite fiber, P311F graphite fiber spacing D002 minimum, and the three porosity from CCM40J, CCM46J to P311F. In order to reduce the high strength and high modulus carbon fiber series, series of the relationship between hardness were: T800SP278FJHT55, P311FCCM46JCCM40J, and the tensile modulus size consistent, characterized by AFM showed that the hardness of carbon fiber can to some extent reflect the tensile modulus of carbon fiber size. The macro mechanical performance is decided by its microscopic structure, smooth surface, fine denier, improve the homogenization degree, retained amorphous structure, is conducive to enhance the strength of carbon fiber; increasing the crystallite size, improve the graphite layer along the fiber axis orientation degree, reduce the porosity can improve graphite fiber modulus.

【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ342.74

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