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对T300碳纤维在真空环境下,在600、900、1200、1500℃进行热处理,用液硅熔渗反应法(liquid silicon infiltration,LSI)制备了不同微观组织结构的C/C-SiC复合材料。采用光电子能谱分析了热处理对纤维表面结构的影响,用光学显微镜和扫描电子显微镜对材料微观形貌进行了观察分析。采用双槽口剪切法(DNS)测试了C/C-SiC复合材料层间剪切强度(interlaminar shear strengh,ILSS),并分析了纤维热处理对材料剪切性能影响的微观机理。结果表明:碳纤维经热处理后,表面化学成分发生变化,氧含量显著降低,改变了碳纤维增强树脂基复合材料(carbon fiber reinforced resin matrix composite,CFRP)先驱体中纤维/树脂界面结合强度,从而在CFRP裂解后形成了具有不同微观结构的C/C预制体,通过液Si对不同微结构的C/C预制体进行熔渗,获得具有不同微观结构的C/C-SiC复合材料;DNS测试发现碳纤维热处理能够有效改善C/C-SiC复合材料的层间剪切强度,主要是由于纤维经热处理后制备的C/C-SiC复合材料中,SiC基体相分布较均匀并包裹在碳纤维周围,导致纤维/基体界面结合强度高。经1500℃热处理纤维增强的C/C-SiC复合材料,其剪切强度为34MPa,与未处理的相比,ILSS提高了33%。
The T300 carbon fibers were heat-treated at 600, 900, 1200 and 1500 ℃ in vacuum environment, and C / C-SiC composites with different microstructures were prepared by liquid silicon infiltration (LSI). The influence of heat treatment on the fiber surface structure was analyzed by photoelectron spectroscopy. The microstructure of the fiber was observed by optical microscope and scanning electron microscope. The interlaminar shear strengh (ILSS) of C / C-SiC composites was tested by double notched shear method (DNS) and the microscopic mechanism of the effect of fiber heat treatment on the shear properties of the composites was analyzed. The results show that the chemical composition of the surface of the carbon fiber changes after heat treatment, the oxygen content is significantly reduced, and the bonding strength of the fiber / resin interface in the precursor of the carbon fiber reinforced resin matrix composite (CFRP) is changed, C / C preforms with different microstructures were formed after cracking, and C / C preforms with different microstructures were infiltrated by liquid Si to obtain C / C-SiC composites with different microstructures. The DNS test showed that carbon fibers Heat treatment can effectively improve the interlaminar shear strength of C / C-SiC composites, which is mainly due to the more uniform distribution of SiC matrix around the carbon fibers in the C / C-SiC composites prepared by heat treatment, resulting in fibers / Matrix interface with high bonding strength. The shear strength of C / C-SiC composites heat-treated at 1500 ℃ was 34MPa, which was 33% higher than that of untreated ones.