Construction Of Carbon Fiber Multi-component Reinforcement And Study On The Properties Of Composites

Carbon fiber(CF)reinforced resin-based composite are widely used in aerospace,military and automobile because of its light weight,high specific strength.With the continuous progress of technology and the continuous growth of social demand,the requirements for CF composites are getting higher and higher.As we all know,CF has fewer functional groups on the surface,chemically inactive and smooth surface,which leads to the failure of good infiltration with resin,reduces the interface performance of the composite material.Thus,the comprehensive properties of the composites largely rely on the the interfacial adhesion between the CF and the matrix.This paper started from the structural design of CF multiscale reinforcerments,and aimed at enhancing the interfacial properties of composites.The different multiscale reinforcements were designed and fabricated by combining metal particles,nano-carbon materials and Mxene materials with CF.The study contents of this paper are as follows:To improve the adhesion between CF and matrix,the electrophoretic deposition method was used to prepare a carbon nanotube/copper/carbon fiber(CNT/Cu/CF)multi-scale reinforcement in two steps,which constructed a interface phase between fiber and resin.The influence of experiment parameters on the interface properties of composites was researched,such as current,time,temperature,etc.,to determine the best preparation conditions.The crystal plane structures of Cu and CNT were investigated via XRD,and SEM was used to obtain the surface morphology of the reinforcement and the corss section of the CF composites.The distribution of elements at the interface was scanned by EDS to prove the formation of the interface phase.Tests by the universal testing machine showed that the interlaminar shear strength of the composite material has increased by 39.5%.The CNT/Cu/CF reinforcement also endows the composites with good thermal conductivity.The test results showed that the thermal conductivity of the composites was increased by 292% after the deposition of CNT for 40 min.As the electrophoretic deposition time continued to increase,CNT appear agglomerated,and a large amount of accumulation was not conducive to the effective transfer of stress and heat.Therefore,the interlaminar shear strength and thermal conductivity of the composites started to show a downward trend instead.Due to the long experimental time and cumbersome process of the two-step electrodeposition method,the CNT/Cu/CF hierarchical reinforcement was prepared by a one-step method.By amination and carboxylation,CNT with positive and negative charges can coexist stably with copper ions which have the same charge in the electrolyte,thereby achieving one-step method.The SEM results of the reinforcement showed that Cu and CNT were deposited on the CF surface at the same time.The Cu particles were uniformly distributed and the gaps between each other were smaller.The results showed that the thermal conductivity and electrical conductivity of the composites prepared by the one-step method were increased by 17% and 20.6%,respectively,compared with the two-step method.The interface performance of CNT/Cu/CF-epoxy composites was increased by34.5% than that of unmodified composites.Graphene oxide(GO)is widely used in composites fillers due to its outstanding mechanical and physical properties.At present,the preparation of hierarchical reinforcements by modifying GO on the CF surface has been widely reported,but the methods used,such as chemical grafting methods,are likely to cause damage to the CF.Hence,the "? bridging" method is used to prepare the graphene oxide/carbon fiber(GO/CF)hierarchical reinforcement.The results of FTIR,XPS and Raman spectra showed that GO is uniformly dispered on the CF surface by the "? bridging" method.SEM and AFM were used to characterize the surface morphologies of the GO/CF,which proved that GO significantly increased the roughness and specific surface area of the fiber.The dynamic contact angle test showed that the surface energy of the fiber was increased by 55.2%,which improves the wettability between the fiber and resin.The interface performance test showed that the interlaminar shear strength,interfacial shear strength and transverse tensile strength of the CF composites modified with graphene oxide increased by 49.3%,59.1%,and 117.1%,respectively.The presence of GO could not only enhance the mechanical locking of fiber and resin,but also improved their chemical compatibility.At the same time,the crack propagation direction at the interface was changed,so that the interface failure form was changed from weak interfacial debonding to cohesive failure.The formation of the interfacial phase between fiber and resin was proved by EDS line scanning of the carbon element at the interface.Moreover,the interfacial bonding perforties could be adjusted by controlling the molar concentration of the bridging agent.MXene/chitosan/carbon fiber(MXene/CS/CF)hierarchical reinforcement was prepared by self-assembly method with mild experimental conditions and simple process.The "organic-inorganic" structural interface layer was constructed of CF and matrix to promote the interface strength of composites.FTIR and Raman spectroscopy were used to characterize the surface chemical structure of the reinforcement.SEM and EDS observed the surface morphology and element distribution of the reinforcement,which proved that MXene and CS were deposited on the CF surface and formed a uniform tight interface layer.The results showed that the interlaminar shear strength and interfacial shear strength of the composites were enhanced by 49.1% and 52.1%,respectively.Finally,the enhancement mechanism of the "organic-inorganic" structure was analyzed and explained.