材料期刊网

将碳纤维视为由微晶和无定型碳所构成的二相复合材料,以Mori-Tanaka方法研究了碳纤维微观结构对弹性模量的影响.对四种高模碳纤维M35JB、M40JB、M46JB及M55JB的微观量进行了测量.微晶的长细比由XRD实验测得,碳纤维石墨化程度由拉曼光谱分析得到.影响碳纤维弹性模量的因素包括:微晶的长细比、体积分数及取向度.通过计算细观力学模型得到了四种高模碳纤维的微晶体积分数.研究发现:碳纤维石墨化程度越高,微晶体积分数越大.碳纤维弹性模量随着微晶取向度、体积分数和长细比的增加而增加,且对这三种因素做了比较,微晶取向度和体积分数对弹性模量的影响高于微晶长细比对弹性模量的影响,只有当微晶取向度接近100%时,其对弹性模量的影响才有可能被微晶长细比超越.微晶取向度和体积分数增加的最初阶段,取向度对弹性模量的影响较大,随着两影响因素的增加,取向度对弹性模量的影响最终被体积分数超越.

Carbon fiber was considered to be a two-phase composite composed of crystallites and amorphous components.The Mori-Tanaka method was used to investigate the relationship between the microstructure of carbon fibers and the tensile modulus of carbon fibers.In order to follow the dependence of the tensile modulus on microstructure, four types of high modulus carbon fibers M35JB, M40JB, M46JB and M55JB were prepared.The aspect ratio of crystallites was measured by XRD and the degree of graphitization was obtained by Raman spectroscopy.Factors that affect the tensile modulus included the aspect ratio, volume fraction and orientation degree of crystallites.The volume fraction of crystallites was obtained by calculating the micromechanical model.It is found that the higher the degree of graphitization is, the higher the volume fraction of crystallites is.Some relationships are concluded that the tensile modulus increases with the increase of the volume fraction, aspect ratio and orientation degree of crystallites.The three factors are compared.The volume fraction and orientation degree of crystallites have a greater effect on tensile modulus than the aspect ratio of crystallites, and it is only when the orientation degree of crystallites approaches 100%, the effect of the orientation degree of crystallites on tensile modulus may be surpassed by the aspect ratio of crystallites.Comparing the volume fraction of crystallites with the orientation degree of crystallites, it can be found that the orientation degree of crystallites has a greater effect than the volume fraction of crystallites in the initial, but with the increase of the two factors, the effect of the orientation degree of crystallites on tensile modulus is surpassed by the volume fractions of crystallites.