短切炭纤维的CVI处理及其在CFRC中的分散性
CVI treatment of short carbon fibers and their dispersion in CFRC
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摘要: 采用CVI法对短炭纤维进行表面处理, 借助超声波对其进行预分散, 用新型分散剂羟乙基纤维素(HEC)和超细粉硅灰对其进行分散, 并研究了其在水泥基体中的分散性; 在SEM电镜下观察了短炭纤维增强水泥基复合材料(CFRC)的断口形貌, 用炭纤维质量变动系数定量评价了短炭纤维在CFRC中的分散性。结果表明, 采用CVI预处理和超声波预分散, 在分散剂HEC和硅灰不同掺量下, 炭纤维的分散性均得到显著改善。炭纤维的分散性随HEC掺量的增加而提高, 当HEC掺量为水泥质量的0.6%、 硅灰掺量为水泥质量的10%时, 两种分散剂的协同作用使炭纤维质量变动系数最小, 此时炭纤维在水泥基体中的分散性最理想。Abstract: The carbon fibers were treated by chemical vapor infiltration (CVI) technology and they were pre-dispersed with the aid of ultrasonic vibration. Both a new dispersant hydroxyethyl cellulose (HEC) and silicon fume were adopted to disperse the carbon fibers in the cement matrix. The fracture surface of CFRC was observed by using SEM to show the dispersion of carbon fibers. The variation coefficient of the mass of separate carbon fibers was applied to evaluate the dispersion of carbon fibers in CFRC. The results show that prior to the adding of dispersants, both CVI surface treatment and pre-dispersion of carbon fibers were helpful for improving the dispersion of carbon fibers. Different mass fractions of HEC and silicon fume in the cement improve the dispersion apparently, which increases with the increasing amount of HEC. The variation coefficient is a minimum when the contents of HEC and silicon fume are 0.6% and 10% in the mixture respectively, at which the dispersion of the carbon fibers is most ideal.