真空气压浸渗3D-Cf/Al复合材料微观缺陷分析

采用真空气压浸渗法制备了纤维体积分数51%、致密度≥97%的三维五向和三维正交编织M40碳纤维增强铝基复合材料(3D-C_f/Al),分析了复合材料中微观缺陷的形貌、形成机理及其控制手段,并对比了2种编织结构对复合材料微观缺陷形成的影响。结果表明:复合材料中的缺陷均是微米级的微观缺陷,主要有束内孔隙、局部纤维偏聚及在基体集聚处的冷隔、显微缩孔及微夹杂等,其中三维正交C_f/Al复合材料束内孔隙及束间孔隙较三维五向C_f/Al复合材料少,而局部纤维偏聚现象较三维五向C_f/Al复合材料严重,造成其缺陷差异的主要原因在于其纤维预制体编织结构的差异,通过提高预热温度可以显著减少复合材料内部的孔隙缺陷及局部纤维偏聚现象。

Micro defects analysis of 3D-Cf/Al composites by vacuum pressure infiltration

The vacuum gas pressure infiltration was performed by 3D five-directional and 3D orthogonal braided performs woven by M40 graphite fiber composite (3D-Cf/Al) with the volume fraction of 51% and the density higher than 97%. After analyzing the morphology and formation mechanism of micro defects and control measures, and comparing the effects of braiding structures on micro defect formation, the results showed that the defects in the composite were micron grade micro defects, of which the main defects included pores within the fiber beam and partial fiber reunited, cold shut, microscopy shrinkage cavity and small inclusion in the substrate concentration. Of note the pores between the fiber beam and pores within the fiber beam of 3D orthogonal composite were less than 3D five-directional composite, while the fiber reunited phenomenon of 3D orthogonal composite was more serious than 3D five-directional composite. The main reason for the different defects was braided structure distinctions. By increasing the fiber preheat temperature could effectively reduce the internal pores defect and partial fiber reunited phenomenon.