Investigation of the properties of carbon fiber / epoxy composite laminates fabricated with CO-RFI process

A co-cured process called co-RFI, which combined resin film infusion (RFI) process and prepreg process was adopted to fabricate carbon fiber/epoxy composite laminates. The different process procedures, including stacks position of RFI part and prepreg part, temperature dwelling and epoxy tackifier were considered and the effects on the processing quality of co-cured laminates were investigated. Moreover, mode I (G_IC) and mode II (G_IIC) delamination fracture toughness were measured to compare the interlaminar property of co-RFI laminates with the property of laminates fabricated by sole prepreg and RFI preform, respectively. The results show that all studied laminates have uniform thickness and high fiber compaction degree. However, resin rich and void defects can be observed in co-RFI laminates by certain conditions. The initial G_IC and G_IIC values of co-RFI laminates locate between those of prepreg laminates and RFI laminates, indicating the interaction of prepreg part and RFI part. Furthermore, a temperature dwell procedure could obviously reduce the resin rich area, increasing the initial G_IC and G_IIC values of co-RFI laminates and RFI laminates. However, utilization of epoxy tackifier may cause the larger resin rich area for co-RFI laminates. The mechanism of results above is discussed from resin flow and permeation of fiber bed.