The effects of microfiller addition on the flexural properties of carbon fiber reinforced phenolic (CFRP) matrix composites were investigated. The CFRP was produced using colloidal silica and silicon carbide (SiC) microfillers, 2 D woven carbon fibers, and two variants of phenolic resole (HRJ-15881 and SP-6877). The resins have the same phenol and solid content but differ in their viscosities and HCHO (formaldehyde) content. The weight fractions of microfillers incorporated into the phenolic matrix are 0.5 wt.%, 1 wt.%, 1.5 wt.%, and 2 wt.%. Flexural properties were determined using a three-point bending test and the damage evolution under flexural loading was investigated using optical and scanning electron microscopy. The results indicated that the reinforcement of phenolic resins with carbon fibers increased the flexural strength of the HRJ-15881 and SP-6877 by 508% and 909%, respectively. The flexural strength of the CFRP composites further increased with the addition of SiC particles up to 1 wt.% SiC but decreased with further increase in the amount of SiC particles. On the other hand, the flexural modulus of the CFRP composites generally decreased with the addition of SiC microfiller. Both the flexural strength and flexural modulus of the CFRP did not improve with the addition of colloidal silica particles. The decrease in flexural properties is caused by the agglomeration of the microfillers, with colloidal silica exhibiting more tendency for agglomeration than SiC. The fractured surfaces revealed fiber breakage, matrix cracking, and delamination under flexural loading. The tendency for failure worsened at microfiller addition of ≥1.5 wt.%.

研究了微量填料添加对碳纤维增强酚醛 (CFRP) 基复合材料弯曲性能的影响。CFRP 是使用胶体二氧化硅和碳化硅 (SiC) 微填料、二维编织碳纤维和两种酚醛树脂变体（HRJ-15881 和 SP-6877）生产的。这些树脂具有相同的苯酚和固体含量，但它们的粘度和 HCHO（甲醛）含量不同。加入酚醛基质中的微填料的重量分数为0.5wt.%、1wt.%、1.5wt.%和2wt.%。使用三点弯曲试验确定弯曲性能，并使用光学和扫描电子显微镜研究弯曲载荷下的损伤演变。结果表明，用碳纤维增强酚醛树脂使 HRJ-15881 和 SP-6877 的弯曲强度分别提高了 508% 和 909%。碳化硅复合材料的抗弯强度随着 SiC 颗粒的添加量达到 1 wt.% 进一步增加，但随着 SiC 颗粒量的进一步增加而降低。另一方面，随着碳化硅微填料的加入，CFRP 复合材料的弯曲模量普遍降低。CFRP 的弯曲强度和弯曲模量都没有随着胶体二氧化硅颗粒的加入而提高。弯曲性能的降低是由微填料的团聚引起的，胶体二氧化硅比 SiC 更倾向于团聚。断裂表面显示纤维断裂、基体开裂、和弯曲载荷下的分层。当微填料添加 ≥ 1.5 wt.% 时，失效趋势恶化。