Multiscale enhancement of carbon/carbon composite performance by self-assembly of sulfonated graphene with silane-treated carbon fibers

Abstract

The application prospects of carbon/carbon composites are greatly limited by interfacial cracks and pores caused by binder pitch displacement and cracking during high-temperature carbonization. In this study, silane coupling agent was coated on the surface of oxygen plasma-treated carbon fibers (CFs) and subsequently electrostatically self-assembled with sulfonated graphene (SG) to improve the interfacial bonding between filler and CTP. The results indicate that the tensile strength of carbon fiber treated with silane coupling agent increased by 19 % compared to untreated CF. This increase in strength may be related to the layer of silane coupling agent that repaired the grooves and imperfections on the CF surface. The addition of SG not only improves the distribution characteristics of the fibers, allowing the silane-treated CF to play a greater role in the matrix, but also creates a three-dimensional hydrogen-bonded cross-linking between the SG and the coal tar pitch (CTP) on the surface of the fibers. This inhibits CTP displacement and pyrolysis, achieving a tight bonding of the fiber to the matrix. The composites' structural integrity and mechanical properties were significantly improved due to the synergistic effect of silane-treated CF and SG. The compressive strength was 216.98 MPa, with a flexural strength of 54.78 MPa, 250 % higher than the untreated carbon fiber-reinforced composites. Additionally, the porosity decreased by 31.5 %, and the antioxidant properties increased. The study presents a potential solution to improve the performance of carbon/carbon composites by using the silane-treated CF-SG multiscale reinforced phase.