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

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.