Study Of Thermo-oxidative Aging On The Durability Of Three-dimensional Braided Carbon/glass Fiber Hybrid Composites

Carbon/glass fiber hybrid polymer matrix composites prepared by the hybrid design and weaving of carbon fiber and glass fiber not only have excellent mechanical performance,but also can reduce the reflection of electromagnetic wave,which is a typical structure-stealth composite material.However,the composites suffer from the decline of the mechanical properties due to the degradation of the matrix and the fiber/matrix interface in the thermal-oxidative environment,bringing safety risks for the subsequent use.In this paper,the stealth,fiber/resin interface,bending,and shear properties of the three-dimensional quasi-isotropic carbon/glass fiber hybrid braided composites(braided composites)and quasi-isotropic carbon/glass fiber hybrid laminated composite(laminated composites)were investigated aging at 200 ℃ and 250 ℃ for 10,30,90,120,and 180 days,respectively.The results show that thermo-oxidative aging has a positive effect on the stealth performance of composites,which is due to numerous cracks and voids on the samples after thermo-oxidative aging.The rough surface of the aged sample makes the electromagnetic wave diffuse reflection on the incident surface,and the cracks and voids could provide additional channels for the electromagnetic wave to enter into the aged samples.In addition,the interfacial performance of the fiber/matrix decreases significantly with the prolonged aging time in a hot oxygen environment,and the interfacial strength retention rate of glass fiber/resin is always greater than the carbon fiber/resin interface.This is because thermal expansion coefficient of carbon fiber and resin is a huge mismatch and the sizing agent(epoxy resin)in the carbon fiber has poor thermal stability.The bending and shear retention rate of braided composites are better than the laminated composite material,which is caused by the presence of Z-binder yarns in the thickness direction of braided composites.Though the properties of matrix and interfacial bonding were degraded due to long-term thermal-oxidative aging,the overall structure of braided composite can still make all fibers bundled together to resist the external load without the lamination failure like laminated composite.Moreover,the “improved stochastic process model” was used to predict the bending strength of braided composites after aging at 200 ℃,and the reliability of the model was verified.This paper contains 32 figures,11 tables and 104 references.