Improvement of atomic oxygen erosion resistance of carbon fiber and carbon fiber/epoxy composite interface with a silane coupling agent

Highlights: • A facile method to improve atomic oxygen erosion resistance for the interface of carbon fiber/epoxy composites was proposed. • Three types of silane coupling agents with different ending groups were used to investigate their effect on the AO erosion resistance. • Both the interfacial adhesion and AO erosion resistance ability of CF/EP composites had an obvious improvement through the generation of SiO₂ on the interface of composites. It is critical for carbon fiber/epoxy (CF/EP) composites to have a high resistance to atomic oxygen (AO) erosion when they are utilized in a low earth orbit (LEO) environment. Herein, we proposed a simple method whereby a silane coupling agent (SCA) was applied onto the carbon fiber surface to fabricate CF/EP composites with both improved interfacial shear strength (IFSS) and AO erosion resistance. The SCA was first hydrolyzed, then reacted with the hydroxyl groups on the pretreated CF surface, and finally formed a continuous uniform layer of siloxane oligomers. Atomic force microscopy images exhibited relatively smooth surfaces for SCA-treated CFs after AO erosion, when compared to the rough surface for bare CFs. It was found that the IFSS and AO erosion resistance were improved for SCA-coated CFs and CF/EP composite interface since a silica (SiO₂) layer was formed upon exposure to AO as confirmed by XPS results.