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采用强度测试、SEM、HRTEM等分析测试手段对纤维表面去碳前后SiC纤维强度、复合材料力学性能、纤维表面形貌、复合材料断口形貌以及复合材料界面特征进行分析表征。结果表明,去碳处理后,纤维表面的固有缺陷暴露出来,纤维强度下降约15%,但由其制备的复合材料强度下降只有原纤维制备复合材料的1/6;复合材料断口非常平整,纤维增韧效果差。分析表明,由于去碳后纤维表面缺陷增多,界面的物理结合增强以及由于基体开裂导致的纤维物理损伤加剧;去碳处理后纤维表面化学反应活性中心明显增加,导致界面化学结合和纤维化学损伤加剧。过强的界面结合和低的纤维就位强度使复合材料力学性能严重恶化。
The strength of SiC fiber, the mechanical properties of the composite, the surface morphology of the fiber, the fracture morphology of the composite and the characteristics of the interface of the composite material were characterized by means of the strength test, SEM, HRTEM and other test methods. The results show that the inherent defects on the surface of the fiber are exposed after the carbon removal treatment, and the strength of the fiber is reduced by about 15%. However, the strength of the composite prepared by the carbon fiber reduction is only 1/6 of that of the fibril preparation composite material; the fracture of the composite material is very smooth; Toughening effect is poor. The results show that the physical bonding of the interface increases and the physical damage of the fiber due to the cracking of the matrix is aggravated due to the increase of the surface defects of the fiber after carbon removal. The chemical reaction center of the fiber surface after carbon removal treatment obviously increases, which leads to the increase of interface chemical bonding and chemical damage of the fiber . Excessive interfacial bonding and low fiber in-situ strength severely degrade the mechanical properties of the composites.