SiC缝合纤维的引入方式对2D SiC/SiC复合材料性能的影响

Effect of the Way to Introduce SiC Sewing Fibers on Mechanical Properties of 2D SiC/SiC Composites

2DSiC/SiC复合材料具有预制体纺织加工成本低及面内力学性能优异等特点,但其层间力学性能较差是影响其在实际构件应用中的最主要因素。借助于自动化数控锁式缝纫系统,采用两种不同缝合纤维引入方式,以相同的缝合密度,用SiC纤维将SiC纤维平纹布缝合成2D SiC纤维预制体,并通过采用先驱体循环浸渍裂解法(PIP)制备出热解碳(PyC)界面2D SiC/SiC复合材料。用高衬度X射线三维显微镜和扫描电镜分析2D SiC/SiC复合材料的显微组织结构,并对其室温层间剪切强度进行了研究。研究结果表明,两种不同缝合纤维引入方式所制备的2D SiC/SiC复合材料密度和孔隙率相近,但相比于用SiC纤维作为缝合面线引入时所制备的复合材料,用SiC纤维作为缝合底线引入时所制备的复合材料的室温弯曲强度提高了12.4%,层间剪切强度提高了20.0%,证明SiC缝合纤维适合作为缝合底线引入。

Although 2D SiC/SiC composites have the advantages of low textile processing cost and excellent in-plane mechanical properties,their poor interlaminar mechanical properties are the main factors limiting their practical applications.Based on automatic CNC sewing system and lock stitch method,SiC fiber preform was sewed by using SiC fibers with two methods to sew the SiC fibers,while sewing density was maintained to be same.The sewing 2D SiC fiber preform with PyC interface was densified through polymer infiltration and pyrolysis(PIP).Microstructure of the 2D SiC/SiC composites was characterized by using micro-CT and scanning electron microscope(SEM).Interlaminar mechanical properties at room temperature were also studied.It was observed that there was no difference in porosity and density between the two groups of 2D SiC/SiC composites.However,as compared with the 2D SiC/SiC composites in which the SiC sewing fiber was introduced as upper thread,those with the SiC sewing fiber to introduced as bobbin thread exhibited enhanced bending strength and interlaminar shear strength,by 12.4%and 20.0%,respectively.It is proved that the SiC sewing fiber to be introduced as bobbin thread is more effective in enhancing mechanical properties of the composites.