| Fiber has large specific surface,aspect ratio,high strength,corrosion resistance,and other excellent properties,and is used as reinforcement of various epoxy resin composites.The fiber surface has high crystallinity,smooth surface,low surface energy and chemical inertia,resulting in poor interfacial properties between carbon fiber and resin.The performance of fiber composites is far lower than that of fiber itself,which seriously limits the performance and application field of fiber-reinforced epoxy resin composites.Therefore,it is necessary to develop new methods of modifying fibers.In order to solve the problem of poor interface bonding between fiber and epoxy resin matrix,this work studies the mechanical,friction and wear,deep-sea corrosion and erosion wear properties of two kinds of polymer modified fiber,discusses the effects of different fiber proportion and different modification methods on the properties of fiber-reinforced epoxy resin composite coating,and analyzes the action mechanism of polymer modified fiber as filler in the erosion process.This paper draws the following conclusions:（1）A method of modifying carbon fiber and aramid fiber by electrostatic self-assembly is proposed.The modified fiber was used to improve the interfacial bonding strength,mechanical properties,wear resistance and erosion resistance of epoxy resin.Through comprehensive experimental characterization,the surface morphology,chemical structure,bonding and erosion mechanism of the materials were deeply understood.Then,the erosion mechanism of silicon carbide and water mixed mortar on the coating was deeply studied.Compared with AF/EP and CF/EP,MAF/EP and MCF/EP improved IFSS by 15.61%and 18.06%respectively.Compared with MAF/EP,the tensile strength of MCF/EP composite coating is increased by 12.13%,and the wear rate and erosion amount are reduced by 62.18%and 50.38%respectively.The results show that the mechanical properties,wear resistance and erosion resistance of MCF/EP composite coating werre significantly improved.MAF fiber and MCF fiber dissipate the impact energy of Si C particles and hinder the further impact of Si C particles by blocking,breaking and peeling.The difference between the two was that the damage of MAF was more serious,forming a"broom"structure to"capture"eroded Si C particles and prevent the continuous impact of subsequent particles on the coating to a certain extent.The damage degree of MCF in the erosion process was relatively light compared with MCF,only slight fracture occurs,and more particles will rebound,reducing the damage degree of erosion particles to the composite coating.（2）Hyperbranched polymer was used to modify carbon fiber to improve the interfacial adhesion between fiber and epoxy resin.Hyperbranched polymer modified carbon fiber（CF-HBP）has the strongest interface performance with resin.The IFSS of CF-HBP/EP was 72.26%higher than that of CF/EP measured by bead debonding test.The high interfacial adhesion between CF-HBP and epoxy resin effectively improved the mechanical properties of the composite coating.Compared with CF/EP,the tensile strength increased by 7.4%and the elongation at break increased by 22.67%.And CF-HBP/EP coating has excellent anti-corrosion performance.After 20 days of immersion in 20 MPa deep-sea corrosion environment,its low-frequency impedance value remains at 1010Ω·cm2,and there was still a good interface between CF-HBP and resin matrix.Moreover,due to the existence of a large number of amino functional groups on the surface of CF-HBP,the cross-linking between fiber and resin forms a network structure,the interface was firmly bonded and hard to fail,so that it has excellent erosion resistance.Compared with pure epoxy resin coating,it was reduced by 25.92%. |
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